SENDOClimbing grade converter
Translate bouldering grades between the V-scale (Hueco), Fontainebleau (Font) and Japanese kyu/dan systems. Pick a grade below for an instant conversion, or scroll down for the full chart — the same mapping the SENDO app uses to normalize your sends across gyms.
Conversions are approximate — the scales don’t line up one-to-one, so some grades map to a range (e.g. V4 ≈ 6B / 6B+).
Why climbing grades don’t translate cleanly
Bouldering never agreed on one ruler. The V-scale grew out of Hueco Tanks in Texas, the Font scale out of the Fontainebleau forest near Paris, and Japanese gyms borrowed the kyu/dan ladder from martial arts. Each was calibrated against different rock, by different climbers, with different resolutions — so converting between them is a translation, not an equation. One V-grade often spans two Font grades (V4 ≈ 6B/6B+), and the kyu/dan ladder skips some V-grades entirely. Any chart that shows a perfect one-to-one match is hiding that.
The V-scale (Hueco)
The V-scale — named after John “Vermin” Sherman — is the standard in North American gyms and much of the English-speaking world. It runs from V0 upward with no fixed ceiling (V17 marks the current outdoor frontier); indoor pads mostly live between V0 and V12. It’s open-ended and purely ordinal: each step up is simply “harder”, with no plus/minus subdivisions in common gym use.
The Fontainebleau (Font) scale
The Font scale is Europe’s reference, born on the sandstone boulders of Fontainebleau. It combines a number, a letter and an optional plus — 6A, 6A+, 6B, 6B+ … — which gives it finer resolution than the V-scale at most levels. That’s exactly why conversions come out as ranges: V4 covers both 6B and 6B+, and V5 covers 6C and 6C+. Watch out for the lookalike French route scale — Font bouldering grades and French sport-climbing grades share notation but are not the same scale.
Japanese kyu/dan (級/段)
Japanese gyms grade like martial arts rank: kyu (級) counts down as difficulty goes up. 10級 is the friendliest problem in the gym, and 1級 (roughly V6) is the hardest kyu. Past that the ladder flips to dan (段), which counts up: 初段 (“first dan”, ≈V7), 二段 (≈V8), 三段 (≈V9) and beyond. Because dan steps are big, the ladder skips some V-grades — there’s no kyu/dan grade that lands exactly on V10 or V12 — so honest conversions snap to the closest rung instead of pretending one exists.
The full conversion chart
One row per V-grade, with its Fontainebleau and kyu/dan equivalents. This is the exact mapping SENDO uses internally to compare grades across systems.
| V-scale (Hueco) | Fontainebleau | Japanese kyu/dan |
|---|---|---|
| V0 | 4 | 10級 / 9級 / 8級 |
| V1 | 5 | 7級 / 6級 |
| V2 | 5+ | 5級 |
| V3 | 6A / 6A+ | 4級 |
| V4 | 6B / 6B+ | 3級 |
| V5 | 6C / 6C+ | 2級 |
| V6 | 7A | 1級 |
| V7 | 7A+ | 初段 |
| V8 | 7B / 7B+ | 二段 |
| V9 | 7C | 三段 |
| V10 | 7C+ | — |
| V11 | 8A | 四段 |
| V12 | — | — |
| V13 | — | 五段 |
“—” means the system has no grade that lands exactly on that V-grade: the Font ladder here tops out at 8A (≈V11), and the kyu/dan ladder jumps from 三段 (≈V9) to 四段 (≈V11) to 五段 (≈V13). All conversions are approximate.
The gym-to-gym caveat
Even inside one system, grades drift. Setters calibrate against their own gym’s clientele, so a V4 at a beginner-friendly commercial gym can feel like a V2 at an old-school bouldering cave — climbers call the first “soft” and the second “sandbagged”. Style skews it further: a slab V4 and a steep, thuggy V4 test completely different climbers. So use conversions (including this one) to orient yourself when you travel, not to settle arguments — and judge your progress over many sessions at the same walls, where the noise averages out.
FAQ
What is V4 in Font grades?
V4 sits in the Fontainebleau 6B–6B+ band. The scales have different resolutions, so one V-grade often covers two Font grades — that’s a range, not a rounding error.
How do Japanese kyu/dan bouldering grades work?
Kyu grades count DOWN as difficulty goes up — 10級 is the easiest, 1級 the hardest kyu (roughly V6). Above 1級 the ladder switches to dan grades, which count UP: 初段 (≈V7), 二段 (≈V8) and so on, like belt ranks in martial arts.
Are climbing grade conversions exact?
No. Every conversion between V-scale, Font and kyu/dan is approximate: the scales were invented in different places with different resolutions, and grading itself varies from gym to gym. Treat any conversion chart as a translation guide, not a measurement.
Why does the same grade feel harder at another gym?
Grades are set by humans, and every gym calibrates its own ladder. A commercial gym’s V4 can climb like another gym’s V2 — climbers call soft-graded gyms “soft” and strict ones “sandbagged”. Comparing yourself across gyms is only meaningful over many climbs, not one.
Log in any system — SENDO does the converting
This chart is baked into SENDO, our free bouldering logger. Your home gym sets in kyu, your trip gym in Font, your friends talk V-grades? Log every climb in the wall’s own system and SENDO normalizes everything underneath — so your grade pyramid, progress trends and hardest-send stats stay comparable across gyms and countries.
Chalk up. Log on.
Your next session deserves a better record than a mental note and a sore ego. Put SENDO on your phone before the next reset.