Kite Line Length & Altitude Calculator
Work out how high your kite is flying from your line length and line angle, and how much line a target altitude needs.
How it works
Altitude = line × sin(angle) + hand height · Horizontal distance = line × cos(angle)
A taut kite line is close to a straight hypotenuse, so basic trigonometry turns line length and the line's angle above horizontal into height and downwind distance. A higher line angle means the kite is flying more directly overhead and reaching greater altitude for the same line, which is the mark of a well-trimmed kite in steady wind. In light or gusty wind the line sags into a curve, so real altitude runs a little below this straight-line estimate.
Worked example
With 100 m of line at a 50° angle and a hand height of 1.5 m, altitude is 100 × sin 50° + 1.5 ≈ 78.1 m, and the kite sits 100 × cos 50° ≈ 64.3 m downwind.
Frequently asked questions
How do I measure the line angle?
Sight along the line and estimate its angle above the horizon, or use a phone inclinometer app aimed up the line. A steady kite in good wind commonly flies at 45–70°.
Why is my kite lower than calculated?
The formula assumes a perfectly straight line. In real conditions the line sags into a catenary curve under its own weight and light wind, so actual altitude is somewhat lower — the error grows with longer, heavier lines.
Are there legal limits on kite altitude?
Many countries cap unpowered kite height near airports and in controlled airspace — in the US the FAA limit is 150 ft without notification. Always check local rules before letting out a lot of line.
Related calculators
This calculator is for educational purposes. Double-check important results before acting on them.