Bouldering grades explained: V-scale, Font, and kyu

Every bouldering gym rates its climbs, but not with the same numbers. Walk into a gym in Denver and the tags say V2. Fly to Fontainebleau and the same difficulty is a 5+. In Tokyo it might be 5級. Three systems, one question: how hard is this thing?

Here’s how each scale actually works, a conversion chart you can trust as far as any conversion chart deserves, and the honest part most guides skip — why the same grade feels completely different from one gym to the next.

How the V-scale works

The V-scale is the bouldering grade you’ll see across North America and most of the English-speaking world. It’s named after John “Vermin” Sherman, who used it to rank the problems at Hueco Tanks in Texas in the early 90s. It’s brutally simple: a single number, starting at V0 and going up. Higher number, harder climb. The current ceiling is V17, held by a handful of boulders worldwide.

Below V0, many gyms add VB — “V-basic” or “V-beginner” — for intro climbs that are closer to a ladder than a puzzle. There’s no letter refinement, so the jumps between grades are big: the gap from V4 to V5 is a real step, not a rounding error. That bluntness is the V-scale’s charm and its weakness.

How the Font scale works

The Fontainebleau scale — “Font” — comes from the boulder-strewn forest south of Paris where the sport more or less grew up. You’ll meet it across Europe and in plenty of gyms elsewhere. It reads like 4, 5, 5+, 6A, 6A+, 6B, 6B+, 6C, 6C+, 7A… — a number for the broad tier, a letter (A/B/C) to split the tier, and a “+” to split it again.

That gives Font much finer resolution than the V-scale, especially in the beginner and intermediate range where most of us live. One V-grade often spans two or three Font grades — which is exactly why converting between them is never quite clean.

One trap for travelers: Font bouldering grades and French route grades look identical on paper (both say things like “6B”) but they are different scales. A Font 6B boulder is much harder than a 6b sport route. Capital letters usually mean bouldering, lowercase means routes — usually.

How Japanese kyu and dan grades work

Japan grades boulders the way martial arts grade belts. The kyu (級) numbers count down as difficulty goes up: 10級 is the easiest, then 9級, 8級, all the way to 1級. Past that, the dan (段) ranks count up: 初段 (first dan, roughly V7), then 二段, 三段 and beyond into the hardest problems in the country.

The “countdown” direction throws people the first time: a 3級 climber is meaningfully stronger than a 7級 climber. Kyu grading is also the most gym-local of the three systems — two gyms in the same city can disagree by a full grade or two, and everyone just accepts that the number belongs to the gym, not the universe.

V-scale to Font conversion chart

With all the caveats above — treat this as a map, not a law — here’s how the three systems line up:

Prefer something you can poke at? The free grade converter uses the exact same mapping as the SENDO app — pick a grade in any system and see its equivalents instantly.

Why the same grade feels different in every gym

Here’s the part that saves you some heartbreak: grades are opinions. Indoors, a grade is one route-setter’s judgment of how the climb compares to the rest of the gym’s set. There is no calibration lab. A few forces pull the numbers around:

• Soft vs. hard gyms. Some gyms grade generously (“soft”) so members feel progress; others under-grade (“sandbagged”) as a point of pride. A V4 at a soft commercial gym and a V4 at an old-school sandbag gym can be two full grades apart.
• Style bias. A slabby, balance-heavy V3 and a steep, powerful V3 demand different bodies. If you’re strong but new to footwork, the slab will feel harder — and vice versa. Same tag, different climb.
• Your height and reach. Setters set for an average body. A long reach can delete a climb’s hardest move; a short one can add a move that isn’t “in the grade”.
• Indoor vs. outdoor. Outdoor grades are almost universally stiffer. A solid V4 gym climber meeting their first outdoor V2 is a rite of passage — and a humbling one.

None of this means grades are useless. It means a grade is most meaningful within one gym’s set, and gets fuzzier the further it travels. (If words like “sandbagged” and “soft” are new, the beginner glossary covers the whole vocabulary.)

So which system should you care about?

The one on your gym’s wall. Fluency in conversions matters exactly once — when you travel — and a converter handles that. What actually moves your climbing is tracking your own progression against your own gym’s grading: the V3 that shut you down in March being a warm-up by June is real data, whatever a chart says it “equals” in Font.

That’s the case for logging climbs consistently: one tap per send builds a record that makes your progress visible even while the grades around you wobble. And if you’re brand new to all of this, start with what to expect at your first session — the grades will make a lot more sense with chalk on your hands.