🪁 Kite Altitude Calculator
From the line you have let out and its angle above the horizon, estimate how high your single-line kite is flying — and how far downwind it sits — in both metres and feet.
🪁 Estimated kite height
Straight-line estimate (altitude = line × sin angle). Real height is a little less: the line's own weight makes it sag into a catenary, so the true angle at the kite is lower than at your hand. Mind local airspace rules and keep well clear of power lines and aircraft — kite flying carries real risks, so use your own judgement.
A little trigonometry on a string
The higher the line angle, the more of your line becomes height rather than horizontal reach. A kite that flies at a steep angle in steady wind climbs far higher on the same line than one that leans downwind in a light breeze.
Steady wind is what lifts a kite to a high, near-vertical angle — check the day with the Wind Speed Converter and Beaufort Scale Guide before you let out the whole spool.
❓ Frequently Asked Questions
How do you work out a kite's altitude?
Treat the line as the straight hypotenuse of a right triangle: altitude = line length × sin(line angle), and horizontal ground distance = line length × cos(line angle). With 100 m of line at 45°, that is about 70.7 m high and 70.7 m downwind; at 30° it is 50 m high; straight overhead (90°) it is the full 100 m.
How do I estimate the line angle?
Sight along the line and judge its angle up from level ground — 0° is along the ground, 45° is halfway up, 90° is straight overhead. A phone clinometer app or simply comparing to the 45° 'halfway' reference gets you close enough for a good estimate.
Why is the real altitude a bit lower than the figure?
Because the line has weight and the wind pushes on it, so it sags into a gentle curve (a catenary) rather than staying perfectly straight. The angle at the kite is a little lower than at your hand, so the straight-line calculation gives an upper bound. The longer and heavier the line, the bigger the difference.
Anything to watch out for?
Yes — mind local airspace and height rules, and keep well clear of power lines, roads, and aircraft. Kite flying carries real risks; these are general estimates, so use your own judgement and fly responsibly.