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About

Climbing grades are subjective estimates of difficulty, varying by region, rock type, and history. This tool uses a normalized Difficulty Index to approximate equivalencies between disparate systems. Unlike simple linear conversion, climbing difficulty often relies on the Crux - the hardest single move - versus the sustained endurance required.

We utilize the Rockfax and UIAA standard comparisons to map Sport, Trad, and Bouldering scales. Note that bouldering grades (V-Scale, Font) are generally harder than their route equivalents because they condense difficulty into fewer moves. For example, a V3 boulder problem might contain moves as hard as a 5.11d route crux.

Formulas

There is no perfect mathematical formula for converting subjective physical experiences, but we can model the relationship using piecewise linear mapping. The approximation between the American YDS (Y) and French (F) systems in the mid-grades can be visualized as:

F ≈ map(Y, Difficulty_Index)

Where Difficulty_Index represents the consensus hardness on a normalized scale of 0 to 100.

For Bouldering (B) vs. Sport (S), the intensity factor (I) implies:

Grade_B ≫ Grade_S for equal move count

Reference Data

YDS (USA)	French	UIAA	Ewbank (AUS)	British (Tech)	Hueco (V)	Font
5.5	4a	IV	12	4a	-	-
5.6	4b	IV+	13	4b	-	-
5.7	4c	V	14-15	4c	-	-
5.8	5a	V+	16	4c	VB	3
5.9	5b	VI-	17-18	5a	V0-	4-
5.10a	5c	VI	19	5a	V0	4
5.10b	6a	VI+	20	5b	V0+	4+
5.10c	6a+	VII-	21	5b	V1	5
5.11a	6b+	VII+	22	5c	V2	6a
5.12a	7a+	VIII+	25	6a	V4	6b+
5.13a	7c+	IX+	29	6b	V7	7a+
5.14a	8b+	X+	32	7a	V10	7c+

Frequently Asked Questions

Grading is subjective. A 5.11a route tests endurance over 20+ meters, while a V2 boulder problem tests raw power over 3 meters. The conversion aligns them by the difficulty of the hardest move (crux), but local grading ethics (e.g., 'Sandbagging') can skew this.

The French scale is primarily for Sport climbing (bolted, focus on athleticism/gymnastics), while UIAA is often used for Mountaineering and Trad climbing in Central Europe, focusing slightly more on danger and natural protection levels.

British Trad has two parts: Adjectival (overall difficulty/danger, e.g., E1) and Technical (hardest move, e.g., 5b). This tool converts the Technical grade, which is the best metric for comparing pure physical difficulty against Sport grades.

Yes. Most gyms use either YDS (USA), French (Europe), or V-Scale (Bouldering). However, gym grades are often "softer" (easier) than outdoor grades to encourage progression.