Temperature Effect on TAS Calculator
Same altitude, same indicated speed, different day: see exactly how many knots of true airspeed a temperature swing adds or removes.
Warm air is a free TAS upgrade โ the same dynamic pressure carries you faster over the ground. The catch: ground speed gains arrive with climb-performance losses; the atmosphere gives and takes from the same account.
Formula
โ ๏ธ For flight planning and education only โ verify with your POH/AFM, certified instruments and official sources. Not for primary navigation or airworthiness decisions.
Same altitude, same indicated speed, different day: see exactly how many knots of true airspeed a temperature swing adds or removes.
About Temperature Effect on TAS Calculator
Two pilots fly identical airplanes at identical indicated speeds and identical altitudes โ in January and July โ and the July pilot files faster estimates. This calculator quantifies the temperature side of true airspeed: enter one altitude and two temperatures and see the TAS on each day, the difference, and the per-degree sensitivity. It's the cleanest demonstration that the airspeed indicator measures pressure, not motion.
How to use Temperature Effect on TAS Calculator
- 1Enter โ 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/โฯ(DA); each ยฐC of warming adds โ 118.8 ft of DA โ +0.2% TAS substituted step by step.
- 4Adjust inputs (or flip the unit toggle) until the scenario matches yours, then copy or share the result.
Why use Temperature Effect on TAS Calculator?
- โInstant, free and private โ every calculation runs in your browser, nothing is uploaded
- โBuilt on the published formula TAS = CAS/โฯ(DA); each ยฐC of warming adds โ 118.8 ft of DA โ +0.2% TAS with sources cited on the page
- โWarm air is a free TAS upgrade โ the same dynamic pressure carries you faster over the ground. The catch: ground speed gains arrive with climb-performance losses; the atmosphere gives and takes from the same account.
- โSwitch units, tweak any input and watch every result update live
Frequently asked questions
How much TAS does each degree of warming buy?+
About 0.2% of your CAS per ยฐC โ roughly a quarter knot per degree for typical cruise speeds. The mechanism: each ยฐC above ISA adds ~119 ft of density altitude, and TAS rises 2% per thousand feet of DA. A 30 ยฐC seasonal swing at cruise altitudes moves TAS by 6โ8 knots.
So is a hot day good for cruise performance?+
For TAS at a given CAS, yes; for everything else, mostly no. The engine produces less power in thin hot air, so the achievable CAS itself drops, often eating the TAS gain. Climb, takeoff and service ceiling all degrade. The net cruise effect depends on whether you fly fixed power or fixed indicated speed โ try our density-altitude tools for the other half of the ledger.
Does winter air really make the airplane feel stronger?+
Measurably: cold dense air feeds the engine more oxygen (more power), the prop more grip, and the wing more lift at lower true speed. The cost is the inverse of this tool's headline โ lower TAS for the same CAS. Pilots' seasonal impressions ('she climbs like a homesick angel in January') are the density ratio talking.
Which temperature do I use โ surface or altitude OAT?+
The OAT at cruise altitude, read from your gauge or the winds-temps-aloft forecast (FB). Surface temperature is irrelevant to cruise TAS except as an input to forecasting the aloft value. A common forecast shorthand is ISA-relative ('ISA+10 at FL080'), which converts directly: ISA at 8,000 ft is โ0.8 ยฐC, so ISA+10 means +9 ยฐC.
Related Field tools
Sunrise & Sunset Calculator
Exact rise, set, solar noon and day length for any place and date โ the NOAA solar equations with the refraction fine print included.
โ LiveGolden Hour & Blue Hour Calculator
Tonight's golden hour and blue hour, computed from sun elevation โ the photographer's light windows with the angles that define them.
โ LiveDay Length Calculator
Hours of daylight for any date and latitude, how fast it's changing, and the swing between your solstices.
โ Live