Standard sea level
110 kt EAS, 0 ft and 15 °C: 110.0 kt TAS.
FLIGHT PLANNING
True airspeed calculator
Turn air density into a clearer picture of your airspeed.
True airspeed118.5 ktDensity-adjusted estimate
Flight conditions
Live calculationSpeed units
kt
EAS; low-Mach CAS approximation onlyft
°C
Your airspeed, resolved.
AIR DATATrue airspeed
118.5kt
Density-adjusted estimate
Density ratio0.862 σ
Pressure altitude5,000 ft
An estimate for dry air using the standard pressure-altitude model.
Report a calculation issue
Describe what you expected. This creates a report you can send to the site maintainer; it does not submit anything automatically.
A LITTLE THEORY
Make sense of your result.
Estimate true airspeed from equivalent airspeed, pressure altitude and outside air temperature.
How to use this calculator
Enter equivalent airspeed (EAS), pressure altitude in feet and outside air temperature in Celsius. CAS is only an approximation for EAS at low Mach.
The formula
TAS = EAS / √σ · σ = (1 − 6.87535 × 10⁻⁶ × h)^5.2561 × 288.15 / (T + 273.15)θ is wind direction minus runway heading or course, normalized to −180° to 180°. V is wind speed. Results round to one decimal; calculations use full precision. Speed units are converted through knots.
PUT IT INTO PRACTICE01 02
Worked examples
Standard day at 5,000 ft
110 kt EAS, 5,000 ft and 5 °C: approximately 118.3 kt TAS.
A few common questions
Can I enter indicated airspeed?+
First correct IAS for instrument and position errors to CAS. At low Mach, CAS approximates EAS; otherwise apply compressibility correction.
Why does true airspeed increase with altitude?+
At lower density, a higher true speed is needed to produce the same dynamic pressure.
A planning aid. Always use your judgement.
Dry-air tropospheric model only, −2,000 to 36,000 ft. Humidity and compressibility corrections are not included; this is not a high-speed air-data computer. This tool does not replace your aircraft operating handbook, official weather, regulations or pilot judgement.
Calculation transparency
Updated 11 September 2026. Automated checks cover the mathematical model; an independent aviation review is pending.
Reference: FAA aviation handbooks · Models and limitations