Convert climbing grades across route and bouldering systems with separate lookup tables, approximate equivalents, and clear discipline-specific context.
How Climbing Grade Conversion Works
Climbing grades are ordered scales, not measurements with a universal equation. The calculator collects every matching entry in the named historical comparison tables. Overlapping grades remain multiple alternatives; missing source values remain unavailable. Route grades stay within the route table, while bouldering grades stay within the bouldering table.
target grade = comparison table[source grade row][target system]
Every result is approximate. A route’s angle, hold type, length, protection, exposure, and local grading tradition can change how hard it feels. British trad grades also include seriousness, so they do not map neatly to sport-climbing systems. A converted value is useful for orientation, but it is not a safety rating or a promise that two climbs will feel identical.
Route Grade Reference
YDS, French, UIAA and Ewbank use explicit cells from UIAA Table 1a (2008). British pairs use the separate Jones, Sharples and Johnson (2018) Table 1 proposal, matched through French grades. These are approximate historical chart comparisons, not a single exact or current universal scale. British pairs above E11 7a in that paper are theoretical.
| YDS | French | UIAA | Ewbank | British chart |
|---|---|---|---|---|
| 5.8 | 4+ | V- | 15 | VS 5a / HVS 4c |
| 5.10a | 6a | Unavailable | 19 | E1 5b |
| 5.11d | 7a+ | VIII | 25 | E5 6b |
| 5.12c / 5.12d | 7c+ | IX | Unavailable | E7 7a |
| 5.14d | 9a | XI | Unavailable | E11 7b (theoretical) |
Bouldering Grade Reference
Bouldering uses a separate lookup because short problems and roped routes test different combinations of movement difficulty, power, endurance, and risk. V/Font comparisons use UIAA Table 6; the independent indicative route context uses Table 6a. Historical Font bands can differ from current local charts. Neither table establishes a climber’s ability or predicts roped performance. Unsupported upper comparisons remain unavailable.
| V-Scale | Font (Table 6) | Indicative YDS context (Table 6a) |
|---|---|---|
| V0 | 5C | 5.9 |
| V3 | 6A | 5.11c/d |
| V6 | 6C–7A | 5.12c (5.12+) |
| V8 | 7B/7B+ | 5.12d–5.13a / 5.13b |
| V15 | 8C | 5.15a (5.15-) |
Example Conversions
For a French 7a route, choose Route grade conversions, select French sport, and enter 7a. The UIAA 2008 explicit row gives YDS 5.11c, UIAA VIII- and Ewbank 24. The separate Jones 2018 chart gives British E4 6b. This comparison does not determine protection or seriousness.
For Font 7A, choose Boulder grade conversions, select Fontainebleau and enter 7A. UIAA Table 6 includes both V6 and V7 in its overlapping bands; both are retained. The separate route-context table is only indicative. It does not certify ability, endurance or safety.
Why Two Charts Can Disagree
Grade conversion charts can differ by a partial grade because the underlying systems developed in different regions and climbing styles. Local guidebooks and gyms may also apply their own conventions. When planning a climb, treat the calculator’s output as a historical chart comparison and consult the route description, local guidebook, and current conditions.
Frequently Asked Questions
Does a converted grade guarantee equivalent difficulty?
No. It is an approximate scale comparison. Technique, style, route length, protection, and conditions can dominate the experience.
Can I convert a route grade directly to a boulder grade?
The calculator deliberately keeps those disciplines separate. Its bouldering table includes route-move context only as a broad explanation, not as a cross-discipline prediction.
Sources
- UIAA — Scales of Difficulty in Climbing, Table 1a (2008), Tables 6 and 6a. Blank cells and overlaps retained.
- Jones, Sharples and Johnson (2018), proposed British pair amendment, Table 1. Entries above E11 7a are theoretical.
- BMC — A brief explanation of UK traditional climbing grades, seriousness and technical difficulty.
