← Back to home

Full reference: metrics & charts

Every scalar metric and every chart produced by the XCCoach flight analyzer, with what each one means, when to look at it, and what you learn from it. Use the search box below to filter the whole page in real time.

Metrics

Numeric KPIs shown as cards on the flight detail page.

Flight identity & metadata

NameDescriptionWhen to lookBenefit
Takeoff / Landing time (UTC)First and last in-air fix of the trimmed flight window.Anytime you need the canonical take-off / landing reference.Aligns every later metric on a single time origin and end.
XC start timeFirst fix considered "on course" — beyond the local launch zone.To split warm-up gaggle from real cross-country flying.Task speed and XC averages stay honest, not diluted by start sequencing.
Total duration (min)Minutes between trimmed take-off and landing.Comparing flights across days & sites.Foundational denominator for every "per-minute" metric.
XC flight duration (min)Minutes spent on course (XC start → landing or task end).To benchmark task speed without the warm-up.Highlights how much of the flight was actually productive XC time.
Analysis versionMarker tying your stats to a specific build of the analyzer.To know whether your numbers were produced by the current methodology.Flags outdated stats automatically and offers one-click re-analyse.

Distance

NameDescriptionWhen to lookBenefit
Total distance (km)Ground-track length — the sum of every GPS segment of the flight.Headline number for any flight.Captures everything you actually flew, including circling.
Straight-line distance (km)Crow-flies distance from take-off to landing.Comparing efficiency vs total km.Anchor for the straight-efficiency ratio.
Straight efficiency (%)Straight-line / total × 100.Days where you doubled back vs days you stayed on a single axis.Quick read on whether you wandered or stayed committed.

Altitude & AGL

NameDescriptionWhen to lookBenefit
Max altitude (m)Highest GNSS altitude touched.Days with rising bases or epic top-outs.Quick check that you actually used the day's ceiling.
Min altitude (m)Lowest GNSS altitude (anti-spike filtered).Reviewing the deepest point of the flight.Pairs with low-save metrics for safety review.
Avg altitude (m)Mean GNSS altitude, time-weighted across the flight.Comparing low-route days vs high-route days.Reveals comfort band you naturally fly in.
Cumulative alt gain (m)Sum of every positive Δalt segment, denoised against tracker noise (baro-preferred).Big-day vs grindy-day comparisons.True elevator-work figure — what you climbed in total.
Net altitude change (m)Landing alt minus take-off alt.Top-landings, bottom-landings, downhill XC.Flags days where you landed below LZ — adds context to glide ratios.
Takeoff altitude (m)GNSS altitude at the first in-air fix.Cross-site comparisons with absolute altitudes.Lets you normalise altitude bands across launches.
Landing altitude (m)GNSS altitude at the last in-air fix.Decoding net altitude change.Pairs with take-off alt for top-vs-bottom landing analysis.
Time below 300 m (min)Total minutes spent below 300 m GNSS altitude.Rough proxy for low-altitude exposure on coastal sites.Useful only near sea level — for AGL exposure use the metric below.
Time < 50 m AGL (min)Minutes within 50 m of real terrain (DEM-based, per-fix).Every flight — flagged red as soon as > 0.The single strongest statistical predictor of incident risk.
Mean AGL (m)Mean DEM-based height above terrain across the flight.Site-style profiling (ridge, mountain, plain).Quantifies how high you actually fly relative to the ground.
Mean thermal entry alt (m)Average GNSS altitude at the start of each thermal.Diagnosing low-and-late entries.If consistently low, you wait too long before committing to a climb.
Mean thermal exit alt (m)Average GNSS altitude when leaving each thermal.Tactical: did you milk the thermal or bail at half-base?Pairs with mean exit % for end-of-climb decision quality.
Evolution stripe (m)Mean thermal-top alt minus mean thermal-entry alt.Tracking conditions improving / deteriorating.Growing positive value = the day fired progressively, useful when grouping flights.

Speed & airspeed

NameDescriptionWhen to lookBenefit
Max ground speed (km/h)Smoothed peak ground speed (anti-spike filtered).Wind-aided dives and tail-wind glides.Sanity-checks the wind speed estimate.
Avg ground speed (km/h)Total distance / XC duration.Quick read on overall pace.Cross-flight comparison of how briskly you crossed.
Max airspeed (km/h)Highest instantaneous airspeed (smoothed peak).Days where you used speed-bar.Quantifies bar use vs theoretical wing speed range.
Total avg airspeed (km/h)Mean airspeed (ground − wind correction) over the whole flight.Wing/pilot calibration over many flights.Reveals your honest cruise speed independent of wind.
XC avg ground speed (km/h)XC circuit distance / first→last TP duration. Identical to Task speed.Comparing tasks across days.The number competition pilots care about — actual round speed.
XC avg airspeed (km/h)Mean airspeed over the XC circuit legs only.Decoding upwind / downwind legs.Filters out wind component to expose pilot-driven pace.
% time on speed-barShare of flight time above the wing's trim airspeed.Aggressive XC days vs leisurely ridge soars.Tracks willingness to push — a tactical maturity indicator.
Speed in glide (km/h)Mean ground speed during glide + float phases.Polar / wind discussions.Pairs with mean sink for glide-quality reading.
Speed in thermal (km/h)Mean ground speed during thermal phases (dominated by drift).Estimating thermal drift sanity.If unexpectedly high, the wind estimate is probably under.

Thermals & climbing

NameDescriptionWhen to lookBenefit
Lifts (n)Number of detected thermal segments after merging short gaps.Comparing days & sites.Fewer-but-stronger vs many-broken signal of the day's structure.
Circles (n)Total full circles across the whole flight.Quantifying time spent rotating.Pairs with lift count to estimate circles per thermal.
Circles / minuteTotal circles divided by total flight duration.Spotting whether you spent the day spinning or moving forward.Indirect efficiency proxy — too high = stuck, too low = not climbing.
Mean vario in thermals (m/s)Time-weighted average climb rate during thermal phases.Day-strength snapshot.The single most useful "was today good?" number.
Max vario (m/s)Highest smoothed climb rate recorded.Strong-day verification.Validates the day's reported potential vs anecdotes.
Min vario (m/s)Deepest sink rate recorded (negative; anti-spike filtered).Worst-air debrief.Flags transitions you'd want to avoid next time.
Best thermal gain (m)Highest single-thermal altitude gain.Highlight reel for the flight.Defines the day's ceiling on altitude per climb.
Mean gain per thermal (m)Average altitude gained per detected thermal.Are you topping out or bailing early?Pairs with exit % to diagnose tactical vs untimely exits.
Longest thermal (min)Duration of the single longest thermal.Glassy / locked-in climbs.Helps identify the conditions where you can stay centred for ages.
Avg circle duration (s)Mean seconds per full circle.Wing-loading and bank-angle discussions.Tighter circles = stronger cores or better wing-loading use.
Vario σ in thermals (m/s)Standard deviation of vario during thermal phases.Comparing your consistency thermal-to-thermal.Lower σ = you replicate climb quality, sign of mature centring.
Thermal efficiency (%)Sum of thermal Δalt (baro-preferred) over cumulative gain.How much of your altitude work happens inside cores.High value = you climb cleanly; low = lots of secondary lift mixed in.
Top-3 thermals vario (m/s)Mean vario of the three best thermals of the flight.Noise-immune day-strength estimate.Less skewed by weak climbs than the mean over all thermals.
Mean thermal exit %Average exit altitude as % of peak per thermal (100 = topped out fully).End-of-climb decisions.Low value = you bail too early; high value = you milk too long.
Mean thermal drift (km)Average horizontal distance between entry and exit of a thermal.Wind-aware tactics.Confirms whether thermals drift more than you think on the day.

Phase distribution

NameDescriptionWhen to lookBenefit
Thermal duration (min)Total time classified as thermal phase.Comparing elevator vs cruise time.High share = climbing-heavy day, low = smooth running.
Glide duration (min)Total time classified as glide phase.Cruise-day comparisons.Pairs with mean glide ratio to read overall flow efficiency.
Float duration (min)Total time in low-vario non-circling phases (transitions in marginal lift).Days where you skimmed without committing.Detects "neither here nor there" floating that costs distance.
Prospect duration (min)Total time circling in lift that didn't qualify as a kept thermal.Days you hunted unsuccessfully.The cleanest measure of wasted time on broken climbs.
Floating share (%)Float duration / (Float + Glide) × 100.Diagnosing transitional indecision.High share = you tend to skim instead of committing — tactical signal.
Gliding time ratio (%)(Glide + Float) / total flight time × 100.Forward-progress read.Higher = more of the flight was actually moving in a chosen direction.

Glide & float

NameDescriptionWhen to lookBenefit
Mean sink in glide (m/s)Average vario during glide phases (negative).Air-mass quality on transitions.Closer to zero = you found lifty air on glide.
Mean glide ratioGlide-phase distance / altitude loss.Headline glide-quality number.Single value to benchmark cross-day cruise efficiency.
Best glide ratioHighest L/D in any single glide segment.Day's "cleanest air" pocket.Sets the ceiling against which mean glide should be read.
Glides (n)Number of detected glide segments.Cruise vs centre comparison.Many short glides = grindy day; few long ones = locked-in.
Max glide distance (km)Length of the longest single glide segment.Standout transitions.Identifies the longest sustained run between climbs.
Longest glide (min)Duration of the single longest glide segment."Endless transition" days.Helps distinguish sky-streets from short glides.
Mean vario in float (m/s)Average vario during float phases.Reading marginal-lift exploitation.If positive, your floats actually gained altitude — good signal.
Longest float (min)Duration of the single longest float segment.Indecision diagnostic.Long floats often signal hesitation between commit / glide.

Tactical pacing & MacCready

NameDescriptionWhen to lookBenefit
Task speed (km/h)XC circuit distance / first→last TP duration.Competition flights.The official scoreboard number — directly comparable across pilots.
Implicit MacCready (m/s)MC implied by your inter-thermal speed vs estimated best-glide speed. Shows "—" when the sample is too small to be reliable.Tactical pace decoding.Tells whether you flew "what your climbs deserved" — too cautious or too brave.
Avg dist between lifts (km)Total distance / number of lifts.Day's structural read.Big spacing = patient day, tight = thermal-soup.
Mean required glide ratioAverage inter-lift off-wind distance / mean alt gain — "what L/D the day asked of you".Validating that the wing was sufficient.If > your wing's polar L/D, you needed lift on transitions to make the day work.
Glide straightness indexWeighted mean of (direct dist / actual dist) per glide segment; 1.0 = perfectly straight.Heading discipline review.Low value = wandering glides costing distance — pure pilotage signal.
Total glide ratio on axisXC circuit distance / cumulative alt gain.End-of-day pacing summary.How many km of XC you bought per metre of climb.
Avg glide ratio (gliding time)Distance during glide+float / altitude loss in those phases.Pure cruise-quality read.Strips out climbing time, isolates how well you glide.

Performance windows

NameDescriptionWhen to lookBenefit
Best 60-min distance (km)Best straight-line distance covered in any rolling 60-min window.Productivity within the prime hour.Length-independent benchmark — comparable across long and short flights.
Best 180-min distance (km)Best straight-line distance over any rolling 180-min window.Sustained productivity.Shows how long you can keep cruising at peak rhythm.

Wind & exploitation

NameDescriptionWhen to lookBenefit
Wind speed (m/s)Estimated from your circling drift, weighted by time. Shows "—" on flights with too little circling to estimate reliably.Sanity-checking forecast vs reality.The wind your wing actually experienced, independent of forecast.
Wind direction (° FROM)Meteorological FROM direction, 0 = N, 90 = E.Cross-checking the forecast direction.Confirms or refutes the briefing's wind-aloft call.
Wind alignment (°)Angle (0–180°) between flight heading and wind-from direction. 0 = pure tailwind.Reading whether you flew with or against the wind.Quick read on whether the day's geometry was favourable.
Transverse effect (°)Angle (0–90°) between circuit axis and downwind direction.Site-vs-wind compatibility.Large value = circuit forced sideways to wind, costing distance.
Circuit axis output (%)XC distance as % of theoretical max wind-aligned distance.Wind-exploitation grade.The single best score for "how well I used the wind today".
Distance lost (km)Kilometres lost due to non-alignment with wind direction.Days that "should have been better".Quantifies the cost of the wrong axis choice.
Off-wind total distance (km)Total GPS distance minus wind effect.Cleaning ground-track from tail/head wind contribution.Pilot-attributable distance, independent of wind drift.
Off-wind XC distance (km)XC circuit distance minus wind effect.Comparing pilot performance across windy and calm days.Levels the field — how far you moved the wing.
Axis ratio (%)XC distance / total off-axis distance × 100.Read of route directness.High value = stayed on axis, low = wandered far from the line.

Turn balance

NameDescriptionWhen to lookBenefit
Left turn %Share of circling time turning left.Bilateral symmetry check.Detects a strong left/right preference — drill candidate.
Right turn %Share of circling time turning right.Bilateral symmetry check.Together with left %, confirms whether you're truly ambidextrous.

Prospecting

NameDescriptionWhen to lookBenefit
Prospecting share (%)Prospect duration / (Prospect + Thermal) × 100.Day-strength diagnostic.High share = many false positives — you commit before confirming.
Mean vario in prospect (m/s)Average vario during prospect phases.Quality of marginal lift you tested.If consistently positive, your false-rejects might have been climbs.
Longest prospect (min)Single longest prospecting segment.Identifying stuck-in-broken-lift moments.Pinpoints the worst time-sink of the flight.
Time lost per lift (min)Prospect duration / number of lifts.Setup-to-payoff ratio.Lower = you confirm cores fast; higher = lots of testing per kept thermal.
Distance lost prospecting (km)Prospect duration × avg on-course speed.Quantifying the geographic cost of broken climbs.Translates "wasted minutes" into kilometres you could have flown.
Potential speed without prospect (km/h)(XC distance + distance lost prospecting) / total duration."What-if" comparison.Upper bound for the day's achievable XC speed if every commit had stuck.

Safety exposure

NameDescriptionWhen to lookBenefit
Low saves (n)Distinct sections where the track dropped below 300 m AGL (DEM-based) AND climbed back ≥ 100 m.Every flight — recurring low saves predict serious incidents.Confronts you with how often you flew yourself out of trouble.
Lowest save AGL (m)Lowest DEM-based AGL during any low-save section.Worst moment of the flight.The single most sobering safety number of the day.

XC scoring

NameDescriptionWhen to lookBenefit
XC flight typeBest circuit category: Free / Out-and-Return / Flat triangle / FAI triangle.Every XC flight.Tells the scoring engine which multiplier applies.
XC distance (km)Best circuit distance — "longest distance on course".Headline XC number.Comparable across days, the canonical "how far".
XC score (pts)XC distance × multiplier (1.0 / 1.2 / 1.4).League rankings.Direct input to FFVL / XContest / CIVL leaderboards.
XC multiplierPer-type multiplier — 1.0 free, 1.2 flat, 1.4 FAI (FFVL default).Knowing which premium your shape unlocked.Reveals the value of pushing for FAI vs settling for flat.
XC turn pointsLatitude, longitude and time of each corner of the optimised circuit.Plotting the scored shape on the map.Drives the map overlay and the leg-by-leg sector analysis.
XC free distance (km)Best free-distance route (1–3 turn points).Comparing route shapes.What you'd get without insisting on a closed loop.
XC out-and-return (km)Best out-and-return — out + back leg sum.Wind-aware route choices.Quantifies the value of returning vs continuing free distance.
XC flat triangle (km)Best flat-triangle perimeter (no leg > 45% of total).Triangle geometry comparison.Smaller leverage than FAI, but easier to close.
XC FAI triangle (km)Best FAI-triangle perimeter (each leg ≥ 28% of total).The premium shape.1.4× multiplier — the highest pay-off geometry.

Tracker quality

NameDescriptionWhen to lookBenefit
Tracker gaps (total s)Sum of seconds across IGC tracklog gaps > 5 s.Diagnosing GPS dropout.Warns when long gaps may bias time-weighted metrics.

Charts

Interactive charts on the flight detail page. Each one targets a specific question.

Core time-series

ChartWhat it showsWhen to lookBenefit
Altitude over timeGNSS altitude vs Unix timestamp.Reading the flight's macro-shape (climb-out, plateau, glide-out).The single most legible "what happened today" picture.
Speed over timeInstantaneous ground speed vs time, smoothed.Bar use, glide-out speed, slow zones.Pairs with vario chart to read tactical pace.
Vario over timeSmoothed vertical speed vs time.Locating climbs and sink zones.The pilot's-eye view of the day's structure.
Baro vs GNSS altitudeBoth altitude sources overlaid.Verifying barometric drift / instrument issues.Catches divergence indicating a calibration or sensor problem.
Airspeed estimateInstantaneous and glide-phase airspeed vs time.Decoding the wing's actual cruise pace.Shows true airspeed independent of head/tail wind.
Tracker qualityGPS recording interval over time.Debugging dropouts.Identifies the timestamps where data went missing.

Distributions & brackets

ChartWhat it showsWhen to lookBenefit
Altitude bracketsTime spent in each 100-m altitude band.Site-style analysis (always low? always high?).Surfaces the comfort band you actually use.
Altitude brackets %Same as above, but as % of flight time.Cross-flight comparisons of altitude usage.Length-independent view of altitude habits.
Phases distributionPie/bar of thermal/glide/float/prospect duration shares.One-glance day character.Climbing-heavy vs cruise-heavy at a single look.
Vario distributionHistogram of vario buckets across the flight.Day-strength signature.Skewed positive = strong day, narrow = mellow.
Time vs varioTime spent in lift / glide per 0.5 m/s vario bucket.Decoding what the day "felt like".Shows where the pilot really spent the day vario-wise.
Turning radius distribution% time in each 10-m turning-radius bracket.Wing-loading / flying-style reading.Reveals tight-and-fast vs wide-and-slow climbing habits.

Per-thermal

ChartWhat it showsWhen to lookBenefit
Thermal rankingPer-thermal gain & mean vario, sorted.Identifying the day's standout climbs.Lets you focus the debrief on the climbs that mattered.
Thermal centeringEarly-vs-late vario per thermal.Reading whether you centred fast.Quantifies "did I get the core early?" as a number per climb.
Thermal entry / exit altitude histogramDistribution of entry and exit altitudes.End-of-climb decisions.Reveals whether you bail consistently low or high.
Thermal exit efficiencyPer-thermal: peak alt, exit alt, exit %, mean vario.Diagnosing premature departures.Identifies the climbs you should have stayed in longer.
Thermal driftPer-thermal drift in km, with duration and gain.Wind-aware tactics.Surfaces strong drift you might not have felt in real time.
Thermal consistencyPer-thermal mean vario and σ.Comparing your repeatability across the day.Lower σ across thermals = mature, stable centring.

Glide & polar

ChartWhat it showsWhen to lookBenefit
Glide ratiosPer-segment L/D for every glide.Reading transition quality.Pinpoints the glides that paid and the glides that bled altitude.
Speed polar (scatter)Airspeed vs sink rate during glide phases.Wing characterisation.Empirical polar — compare with the manufacturer curve.
Glide efficiency vs polarPer glide: actual L/D, theoretical L/D from polar, efficiency %.Air-mass quality reading.> 100% = you flew in lifty air; < 100% = sink across the glide.
HoveringRolling glide+float share over time (forward-travel %).Reading commitment cadence.Drops in the curve mark hesitation / float-heavy stretches.
Glide heading rosePolar histogram of GPS bearings during glide phases (16 sectors).Cross-checking actual headings vs intended axis.Confirms whether your glides really followed the chosen course.
Inter-lift glide ratioL/D between consecutive thermals.Day-by-day quality check.Direct read on transition efficiency between climbs.

Wind

ChartWhat it showsWhen to lookBenefit
Wind & speed on courseOn-course speed plus wind tail component over time.Decoding leg-by-leg pace.Shows where the wind was helping or hurting your run.
Course & directionPilot heading deviation overlaid with wind direction.Heading-discipline review.Surfaces drifts away from the chosen line.
Wind per thermal (×4 views)Per-thermal estimated wind; drives evolution, altitude, hodograph and time-rose views.Cross-day wind-aloft tracking.The hodograph by altitude is the single most informative wind-shear chart.

XC progress

ChartWhat it showsWhen to lookBenefit
Linear distanceCumulative ground-track distance over time.Pacing review.Flat segments highlight time spent climbing vs gliding.
Linear course distanceCumulative on-course distance over time.Comparing real vs planned progression.Strips wandering from the headline km figure.
Course variationDeviation from a linear GPS / airspeed pace.Reading consistency.Spots the periods you sped up or slowed down vs your average.
XC progressRunning max on-course distance over time.Quantifying when distance was banked.The classic "stair-step" XC chart — when did the kilometres come.
Distance made good / hourHourly buckets of usable XC kilometres.Comparing morning vs afternoon productivity.Reveals the prime hour and the dead hour of the flight.
Sector speedsPer-leg distance, time, speed.Competition debrief.Pinpoints the leg that broke the round.

Hourly views

ChartWhat it showsWhen to lookBenefit
Hourly mean varioMean climb rate per clock hour.Day-arc reading.Quantifies when the day fired and when it died.
Hourly speedSliding 1-hour avg ground speed and on-course speed.Pace comparison across the flight.Surfaces the hour you really moved.
Hourly airspeedSliding 1-hour avg airspeed.Wing/pilot pacing across the flight.Wind-corrected version of hourly speed.
Hourly lift share% time in lift per clock hour.Day-strength evolution.Shows how much each hour was "in the elevator".
Hourly prospect share% time prospecting per hour.Quality of the day's lift over time.Signals when you were testing more than committing.
Hourly float share% time floating per hour.Indecision tracking.Highlights the hour you spent neither circling nor gliding.
Hourly glide share% time gliding per hour.Cruise-window mapping.Pairs with hourly lift share to reconstruct the day's rhythm.
Evolution stripeThermal entry & peak altitudes over time.Conditions improving / deteriorating.Visual proof of "the day picked up" or "ceiling collapsed".

Phase deep-dives

ChartWhat it showsWhen to lookBenefit
Prospect altitudesMean altitude per prospecting phase.Are you prospecting too high or too low?Surfaces a habit of testing weak lift in the wrong band.
Prospect alt gainsNet alt gain/loss per prospecting phase.Quality of the lift you tested.If many segments end positive, your "rejects" might have worked.
Float altitudesMean altitude per float phase.Floating habits across altitude bands.Shows where you tend to skim instead of commit.
Float alt gainsNet alt gain/loss per float phase.Reading low-energy gain potential.Some floats actually climb — this chart finds them.
Lift share per altitude% time in lift per 100-m altitude bracket.Where the day's elevator works.Identifies the band you should target on the day.
Mean vario by alt thirdMean vario in each altitude-range third (low/mid/high).Ceiling-band quality check.If top third is the strongest, you should commit higher.
Mean thermal vario by alt thirdSame as above, restricted to thermal+prospect phases.Pure climbing-air read.Strips out cruise to expose where lift was strongest.
Mean vario per altitude bracketMean vario per 100-m altitude bracket.Fine-grained ceiling exploitation.Granular version of the band-quality reading.

Spider, ambidexterity & behaviour

ChartWhat it showsWhen to lookBenefit
Efficiency spider8-axis radar comparing your flight to a level benchmark.End-of-flight summary.One picture summarises which axes performed and which lagged.
AmbidexterityLeft/right turning split across the flight.Symmetry diagnostic.Surfaces a side preference quickly.
Ambidexterity detailRadius distribution split L/R + mean vario per side.Decoding why one side performs better.If one side has tighter radius and stronger vario, drill the other.
Stress signatureBehavioural indicators across 5 families (motor / decision / escape / breakpoint / context) plus a composite 0–100 score.Fatigue and tunnel-vision pattern detection.Catches behavioural drift you didn't feel during the flight.

Events & energy

ChartWhat it showsWhen to lookBenefit
Energy budget per phaseNet change of kinetic and potential energy summed per phase type, in absolute kJ.Reading where energy was actually banked or burned.Connects vario and speed into a single physics-true picture.
Low-save detailsPer low-save event: time, lowest AGL, duration, climb regained.Safety review.Annotated table that drives the safety findings on the page.
Missed climbsPer detected missed climb: thermal n, exit alt, tail vario, estimated missed gain."What you left on the table".Quantifies premature exits with a metres-of-altitude estimate.

Map & phase ribbon

ChartWhat it showsWhen to lookBenefit
Track (lat/lon)Downsampled track for the map overlay (≈ 1500 points max).Map view, multi-flight overlay.Light-weight geometry that still captures the flight shape.
Phase timeline (ribbon)Coloured segments for each phase, indexed in seconds since take-off.Comparing flights side-by-side.Two flights aligned on the same time axis tell their story instantly.
Airspace crossingsDetected airspace traversals with times, altitudes and class.Compliance review.Surfaces violations you may not have spotted while flying.

Need more depth on any single metric? Open the flight detail page in the app — every numeric KPI carries a hover tooltip with the formula, the source data, and the unit.