Which kite size do you need? It comes down to two numbers — how much you weigh and how hard the wind blows — plus the board you ride. Move the sliders for an instant answer, then read how the rule of thumb works and when to go a size up or down.
📖 3 min read · Updated September 2026 · By Sergei Sharvarok · Founder & Head Instructor
Kite Size Calculator
Range: 10–12 m · Wind: 7.7 m/s · 28 km/h
Rule of thumb for steady wind. Gusty days, your skill level and the kite model all shift the answer — in lessons the instructor chooses the size for you.
How the Calculation Works
The calculator uses the rule of thumb most instructors start from: kite size (m²) ≈ rider weight (kg) ÷ wind speed (knots) × 2.2 for a twin-tip. A 75 kg rider in 15 knots gets 75 ÷ 15 × 2.2 = 11 m. Heavier riders and lighter wind push the number up; lighter riders and stronger wind push it down.
The board changes the factor. A surfboard or directional is ridden with a little less power, so the factor drops to about 2.1. A hydrofoil lifts out of the water at low speed and needs far less pull, so the factor falls to around 1.4 — which is why foil riders are out on a 7 m kite when twin-tip riders are waiting for more wind.
Kite Size Chart: Weight × Wind (Twin-Tip)
| Rider weight | 12 kts | 15 kts | 18 kts | 21 kts | 25 kts |
|---|---|---|---|---|---|
| 50 kg | 9 m | 7 m | 6 m | 5 m | 5 m |
| 60 kg | 11 m | 9 m | 7 m | 6 m | 5 m |
| 70 kg | 13 m | 10 m | 9 m | 7 m | 6 m |
| 80 kg | 15 m | 12 m | 10 m | 8 m | 7 m |
| 90 kg | 16 m | 13 m | 11 m | 9 m | 8 m |
| 100 kg | 17 m | 15 m | 12 m | 10 m | 9 m |
Sizes are rounded to whole metres and limited to the usual 5–17 m range. Between two sizes? In gusty wind take the smaller one; in steady, light wind the bigger one.
When to Go a Size Up or Down
- Gusty wind — size for the gusts, not the lulls. Getting overpowered is the most common way a session goes wrong.
- Your level — beginners are better off slightly underpowered; the instructor chooses a size that keeps the kite manageable while you learn.
- The kite model — a big-air kite and a light-wind freeride kite of the same size do not pull the same. Treat the calculator as a starting point.
- Water state — flat water feels faster and easier; choppy water needs a little more power to keep the board moving.
Rig for where the wind is heading, not where it is when you pump. If the forecast shows the breeze building through the afternoon, start one size smaller.
Kite Sizes for Koh Samui
From December to April we ride at Nahai Beach, where the NE and then E–SE wind typically blows 12–20 knots — most consistent from January to March. For a 70–80 kg rider on a twin-tip that usually means a 9–12 m kite. From May to October the school moves to Nathon Beach on the west coast; the SW monsoon is lighter and more variable (10–18 knots), so bigger kites and foils come out more often.
Building a quiver for Samui? For an average-weight rider, two kites around 9 m and 12 m cover most riding days of the Nahai season.
Not sure yet? Rent before you buy: our kite rental lets you try different sizes in local wind, and we are the official Slingshot distributor on the island — see the current kite range.
Frequently Asked Questions
What size kite do I need for 75 kg?
In 15 knots a 75 kg rider on a twin-tip usually rides about an 11 m kite. In 20 knots it drops to about 8–9 m, and in 12 knots it rises to about 13–14 m.
How do I calculate kite size?
Divide your weight in kilograms by the wind speed in knots and multiply by about 2.2 for a twin-tip, 2.1 for a surfboard or 1.4 for a hydrofoil. The result is the kite size in square metres.
Which kite size is best for beginners?
Beginners do not need to choose: in lessons the instructor picks the size for your weight and the day. As a rule, learners are safer slightly underpowered than overpowered.
How many knots is too little wind to kite?
Below about 12 knots a twin-tip needs a very big kite and a lot of technique. A hydrofoil works in much lighter wind.
Not Sure Which Size?
Send us your weight, level and dates — we will tell you which kite suits Samui wind.
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