Aviation calculators

The flight-computer problems, worked properly — with the rule of thumb shown alongside the exact answer, so you can see how far off the mental version is.

Live weather

• Live weather extremes worldwide

  Lowest visibility, lowest ceilings and strongest winds being reported anywhere on Earth right now — plus the most complex METARs in circulation. Tap any group to decode it.

Atmosphere and performance

• Density altitude calculator

  The altitude your aircraft performs as if it were at. Shows pressure altitude, ISA deviation and density ratio.

• Pressure altitude calculator

  Field elevation and altimeter setting to pressure altitude — the input to nearly every performance chart.

• True airspeed calculator

  CAS to TAS for a pressure altitude and temperature, with Mach number.

• Cloud base calculator

  Convective cloud base from the temperature–dewpoint spread, plus a fog-risk read.

Wind

• Crosswind component calculator

  Split the reported wind into runway and across-runway components, including the gust.

• Wind correction angle and groundspeed

  The wind triangle: what heading to steer and how fast you will actually travel.

Planning and profile

• Time, speed and distance

  Leg time and fuel, with reserves and fuel weight.

• Top of descent calculator

  Where to start down and at what rate, against the 3-to-1 and ×5 rules of thumb.

• Climb gradient calculator

  Feet per minute to feet per nautical mile and percent — and whether you make a published departure gradient.

• Glide distance calculator

  How far you reach with the engine out, with wind, and why the number is optimistic.

Conversion

• Aviation unit converter

  Distance, speed, altitude, weight, volume, fuel weight, pressure and temperature.

About these calculators

Each one uses the real formula rather than the rule of thumb, and shows the rule of thumb next to it. Pilots use the mental version in the air, and it is worth seeing where it holds and where it drifts — the 2%-per-1,000-ft airspeed rule and the 120-ft-per-degree density altitude rule are both close in ordinary conditions and both wander when conditions are not ordinary.

Standard atmosphere values are ISA throughout: 15 °C and 1013.25 hPa at sea level, lapsing 1.98 °C per 1,000 ft. Every page shows its formula and a worked example.