Short answer, for a rider around 75–80 kg on a twintip: 10 knots wants a 13m, 15 knots an 11m, 18 knots a 9m, 20 knots an 8–9m, 25 knots a 6–7m, 30 knots a 5m. The rule underneath those numbers: your wind should sit about 4–6 knots above the bottom of the kite's published range — not in the middle of it.
The lookup
North publishes a wind range for every size it makes. Reading it backwards — from the wind you get to the size you need — gives this. The right-hand column is North's own figure for that size on the Reach 2025 spec sheet, so you can check the arithmetic:
| Wind you actually get | Kite size (75–80 kg rider) | North's published range for that size |
|---|---|---|
| 10 knots | 13m | 8–20 kn |
| 12–13 knots | 12m | 9–23 kn |
| 15 knots | 11m | 10–25 kn |
| 18 knots | 9m | 14–28 kn |
| 20 knots | 8m or 9m | 16–30 kn / 14–28 kn |
| 25 knots | 6m or 7m | 20–34 kn / 18–32 kn |
| 30 knots and up | 5m | 22–37 kn |
Why 4–6 knots above the bottom, and not the middle
North's published bands are wide — most Reach sizes cover 14 knots end to end. The bottom of the band is where the kite will just fly and drag you upwind; the top is where a good rider survives on full depower. Neither is where you want to spend a session.
Sitting 4–6 knots above the bottom puts you in the part of the range where the kite has real power in the lulls, still has depower left for the gusts, and relaunches without a fight. That is why a 9m Reach, rated 14–28 knots, is the kite most riders reach for at 18–20 knots rather than at 21, the arithmetic middle.
Your weight moves every row
These rows assume the rider North's tables assume: roughly 75–80 kg. Heavier than that, move one size up, or read the whole table about 2–3 knots to the right. Lighter, move one size down. North is explicit about this on its light-wind sizes — the Reach 13m, 15m, 17m and 19m all carry the same 8–20 knot rating, and the only thing separating them is the rider weight column: under 70 kg, 70–85 kg, over 85 kg, over 100 kg.
Below 12 knots is a different question
At 10 knots and under, a bigger twintip kite stops being the answer and a light-wind specialist starts being one. North rates the Code Zero Pro 2025, a single-strut ultralight, at 8–19 knots in the 8m and 7–17 in the 10m behind a foil — several knots lower than any Reach size, because there is far less kite to hold up. As of this post it runs about $955–$1,195. If your spot is genuinely light most days, that is a better purchase than the biggest Reach you can afford.
Honest limit: "20 knots" on a forecast app and 20 knots on the water are different things. Gusty, thermally offshore wind that spikes 12 to 24 wants the size you would pick for the lulls, not the average. Chop pushes your practical low end up a knot or two. Board size shifts it back down. And a rider still learning to sheet out will feel maxed well before the top of any band. The table gets you to one or two sizes; conditions decide between them. Our gear advisor takes your weight, your spot and your usual wind and returns a single size, and every model's full table is on the kite sizing page.
What fits these sizes
As of this post, the Reach 2025 covers 5m through 12m at about $1,033–$1,189, and the Reach 2026 runs the full 5m–19m ladder at about $1,579–$2,729. For the same wind on a big-air kite, the Orbit 2026 ($1,375–$1,759) is rated a few knots wider at the top — 9m at 14–32 knots against the Reach 9m's 14–28 — which is worth knowing if your 20-knot days regularly turn into 28-knot days.
No North kite includes a bar or a pump. Bar length follows kite size: S 38–43cm under 8m, M 45–50cm under 11m, L 50–55cm above 8m, from the Navigator control systems.
FAQ
What size kite for 20 knots?
An 8m or 9m for a 75–80 kg rider. North rates the Reach 8m at 16–30 knots and the 9m at 14–28, so 20 knots sits comfortably inside both — take the 9m if you are heavier or the water is choppy, the 8m if you are light or the wind is gusty on top.
What size kite for 15 knots?
An 11m, rated 10–25 knots. A 12m (9–23) works too and will get you going earlier; an experienced 80 kg rider on a big board can make a 10m (12–26) work at 15.
Is 10 knots enough to kite?
On a twintip it is marginal — you are at the bottom of even a 13m's 8–20 knot rating. On a foil, or on a light-wind kite like the Code Zero Pro rated 8–19 knots in the 8m, 10 knots is a session.