HesapHanem

Ground Speed With Wind Calculator

Enter true airspeed, heading and the wind direction and speed.

How it is calculated

The tool takes the angle between the wind direction and your heading, θ = wind_dir − heading (degrees), and splits the wind into two parts: headwind = wind_speed × cos θ and crosswind = wind_speed × sin θ. Ground speed is GS = TAS − headwind. All speeds are in knots and angles in degrees. Wind direction is the direction the wind blows from, so a wind equal to your heading is a pure headwind, and a negative headwind figure is a tailwind. The crosswind is shown as an absolute value, without a left or right side. TAS must be above zero and wind speed cannot be negative. The tool does not apply a wind-correction (crab) angle, so with a strong crosswind the result is slightly higher than a full wind-triangle solution.

Worked example

Heading 90° (east), TAS 120 kt, wind from 45° at 20 kt. The angle between wind and heading is 45 − 90 = −45°. Headwind = 20 × cos 45° = 14.1 kt and crosswind = 20 × sin 45° = 14.1 kt (shown as a positive number). Ground speed = 120 − 14.1 = 105.9 kt. The wind from the north-east slows the aircraft by about 14 kt along its track.

Try this example →

Common mistakes

  • Entering the direction the wind is blowing to instead of where it comes from. A westerly wind (from 270°) is a tailwind on an eastbound heading, and the tool will show it that way only if you enter 270.
  • Mixing up heading and track or true and magnetic north. Wind direction and heading must use the same reference.
  • Entering speeds in km/h or mph. The labels are knots, so convert first, otherwise the ground speed is wrong.
  • Reading a negative headwind as an error. It means a tailwind, which raises ground speed above TAS.
  • Expecting the crosswind to tell you left from right. It is always positive, so work out the side from the angle yourself.

About this calculator

An aircraft's true airspeed (TAS) is its speed through the air mass, but the air mass itself is moving relative to the ground, so the aircraft's actual ground speed differs from TAS. A full solution is classically done with the wind triangle in flight planning and dead-reckoning navigation; this calculator uses the simpler along-track approximation: ground speed = TAS − headwind component, with the wind direction being where the wind blows from and speeds in knots. It does not solve the wind correction angle.

Breaking the wind into components relative to the aircraft's heading — a headwind/tailwind component (wind speed × cosine of the angle between wind direction and heading) and a crosswind component (wind speed × sine of that angle) — shows how much the wind slows or speeds the aircraft along its path versus how much it pushes it sideways, requiring a heading correction to stay on course. Pilots use this before every flight to estimate time en route and fuel burn accurately.

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Comments (1)

  • Editorial team

    Wind direction means where the wind blows from, and the tool takes the headwind component along your heading without solving for the correction angle needed to hold a track. The ground speed is therefore an approximation that drifts further from reality as the crosswind grows. Treat it as a sanity check, not flight planning. Do you want a version that solves for wind correction angle?

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