US letters to millimeters
Type a value in US letter to get it in mm instantly.
4mm
That's 1.07× as thick as the hook for sport yarn, while the hook for DK yarn is 1.13× thicker.
Convert the other way: mm to US letter
What it means
Which yarn suits that hook?
Steel hooks for thread use a separate, reversed numbering and are not covered here. Brands differ slightly above 6 mm.
The math
How to convert US letter to mm
Hook sizes are a table: H-8 = 5 mm, G-6 = 4 mm, J-10 = 6 mm. The letter and the number name the same hook.
Example: G-6 US letter = 4 mm.
Every unit
That hook in every system
Tables
US letter to mm conversion table
| US letter | mm |
|---|---|
| B-1 US letter | 2.25 mm |
| C-2 US letter | 2.75 mm |
| D-3 US letter | 3.25 mm |
| E-4 US letter | 3.5 mm |
| F-5 US letter | 3.75 mm |
| G-6 US letter | 4 mm |
| 7 US letter | 4.5 mm |
| H-8 US letter | 5 mm |
| I-9 US letter | 5.5 mm |
| J-10 US letter | 6 mm |
| K-10.5 US letter | 6.5 mm |
| L-11 US letter | 8 mm |
| M/N-13 US letter | 9 mm |
| N/P-15 US letter | 10 mm |
mm to US letter conversion table
| mm | US letter |
|---|---|
| 2.25 mm | B-1 US letter |
| 2.75 mm | C-2 US letter |
| 3.25 mm | D-3 US letter |
| 3.5 mm | E-4 US letter |
| 3.75 mm | F-5 US letter |
| 4 mm | G-6 US letter |
| 4.5 mm | 7 US letter |
| 5 mm | H-8 US letter |
| 5.5 mm | I-9 US letter |
| 6 mm | J-10 US letter |
| 6.5 mm | K-10.5 US letter |
| 8 mm | L-11 US letter |
| 9 mm | M/N-13 US letter |
| 10 mm | N/P-15 US letter |
Quick answers
Quick answers
- How many mm is B-1 US letter?
- B-1 US letter is 2.25 mm.
- How many mm is J-10 US letter?
- J-10 US letter is 6 mm.
- How many mm is G-6 US letter?
- G-6 US letter is 4 mm.
The units
About these units
US letters (US letter)
B-1 to N/P-15. Type the letter: H, K or M/N.
Millimeters (mm)
The diameter of the shaft.
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