True Airspeed Calculator (km/h, Metric)
TAS for the km/h world — microlights, gliders and European ultralights — with metric altitude and the same exact ISA math underneath.
Glider polars quote speeds in km/h and sink in m/s — this tool speaks both. At 2,400 m on a cool day your 180 km/h indicated is nearly 205 km/h true, which is what the final-glide computer needs to know.
Formula
⚠️ For flight planning and education only — verify with your POH/AFM, certified instruments and official sources. Not for primary navigation or airworthiness decisions.
TAS for the km/h world — microlights, gliders and European ultralights — with metric altitude and the same exact ISA math underneath.
About True Airspeed Calculator (km/h, Metric)
European ultralight cockpits, glider polars and FAI record claims all speak kilometres per hour, while most TAS calculators stubbornly think in knots. This one is metric-native — km/h airspeed, metres of altitude, m/s output for the sink-rate crowd — wrapped around the identical exact ISA density math, with a knots toggle for crossing the channel.
How to use True Airspeed Calculator (km/h, Metric)
- 1Enter — sensible defaults are pre-filled so you see a worked result immediately.
- 2Read the live results: .
- 3Check the "With your numbers" line to see the formula TAS = CAS/√σ; σ = δ(PA)/θ(T) — units merely dressed in km/h and metres substituted step by step.
- 4Adjust inputs (or flip the unit toggle) until the scenario matches yours, then copy or share the result.
Why use True Airspeed Calculator (km/h, Metric)?
- ✓Instant, free and private — every calculation runs in your browser, nothing is uploaded
- ✓Built on the published formula TAS = CAS/√σ; σ = δ(PA)/θ(T) — units merely dressed in km/h and metres with sources cited on the page
- ✓Glider polars quote speeds in km/h and sink in m/s — this tool speaks both. At 2,400 m on a cool day your 180 km/h indicated is nearly 205 km/h true, which is what the final-glide computer needs to know.
- ✓Switch units, tweak any input and watch every result update live
Frequently asked questions
Why do gliders care about TAS at all without engines?+
Final glides and speed-to-fly. A polar measured at sea level shifts with density: the same indicated best-glide speed is a higher true speed (and the same true sink) at altitude, changing achieved glide over the ground. Flight computers do this silently; pilots flying classic instruments do it with this arithmetic.
How do km/h cockpits handle the IAS/CAS distinction?+
Identically to knot cockpits — the units don't change the physics. The POH/flight manual's calibration table converts IAS to CAS in km/h; the σ correction then yields TAS. For most ultralights cruising below 200 km/h the position error is small, but near Vne it can matter for the very record attempts that demand TAS.
What's the quick metric mental rule for TAS?+
Add 1% per 600 m of altitude — twin of the imperial 2%-per-1,000-ft. At 2,400 m that's +4×... careful: 2,400/600 = 4, but each step is 2% in imperial terms scaled: use +2% per 600 m. So 2,400 m → +8%: 180 km/h indicated ≈ 194 true on a standard day. This calculator shows the exact answer beside the estimate's territory.
Why does the tool also output metres per second?+
Because soaring instruments mix units deliberately: speeds in km/h, climb and sink in m/s (a 2 m/s thermal, a 1 m/s netto). Converting TAS to m/s (divide by 3.6) lets you place forward speed and vertical speed in the same unit for glide-angle and McCready reasoning without a second tool.
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