How to read belt codes
How to read the profile, length and width in belt codes such as B62, SPZ 1250, 6PK1450 and 8M-920 30, by belt type.
Last updated: 6 November 2026
A belt code gives the profile and length, and how you read it depends on the belt type. The code is usually printed on the back of the belt.
Classical V-belts: Z, A, B, C, D
Two forms are used side by side: B62 or 17X1575. The letter is the profile and the number is the length in inches (62 × 25.4 ≈ 1575 mm). In the metric form, the first number is the top width and the second is the length.
| Profile | Top width |
|---|---|
| Z | 10 mm |
| A | 13 mm |
| B | 17 mm |
| C | 22 mm |
| D | 32 mm |
Cogged belts add an X to the letter, as in AX49.
Narrow V-belts: SPZ, SPA, SPB, SPC
SPZ 1250 means SPZ profile with a 1250 mm datum length (Lw).
| Profile | Top width |
|---|---|
| SPZ | 9.7 mm |
| SPA | 12.7 mm |
| SPB | 16.3 mm |
| SPC | 22 mm |
Cogged versions are written XPZ, XPA, XPB and XPC.
Ribbed belts: PJ, PK, PL
6PK1450 means 6 ribs, PK profile and a length of 1450 mm. The number of ribs sets the width of the belt.
Timing belts
8M-920 30 means an 8 mm tooth pitch, a length of 920 mm and a width of 30 mm. The number of teeth is the length divided by the pitch: 920 ÷ 8 = 115 teeth. 3M, 5M, 14M and T10 read the same way.
On inch belts, 255L075 means a length of 25.5 inches (647.7 mm), L profile and a width of 0.75 inch (19 mm). The tooth pitch is 5.08 mm for XL, 9.525 mm for L and 12.7 mm for H.
On automotive timing belts, 103 RP 240 means 103 teeth, RP profile and a width of 24 mm.
If the code has worn off
- Measure the top width with a caliper.
- Measure the outer length with a tape. An old belt may have stretched, so compare the result with the nearest standard size.
- On a timing belt, count the teeth; this is more accurate than the length.
Enter the code in the Belt & seal finder; spacing and hyphen differences do not matter.