How To Measure V Belts Correctly - Determine My V Belt Size

How To Measure V Belts

Belts are NOT measured by diameter nor folding the belt in half. The most accurate way to measure the circumference of a v belt is with a v belt measuring tool or using a cloth tape measure (Not a steel tape measure or ruler). An additional option is to wrap a small diameter string/rope around the belt, then measure the length of the string. When measuring be sure to have the belt under slight tension and the cloth tape measure is tightly against the back of the belt. Also, keep in mind belts do stretch and unfortunately there is no specific value for how much a belt can stretch. You'll also need to measure the width and depth to determine which section v belt you have.

Classic & Kevlar V Belt Sections

3L Section - 3/8" Width X 7/32" Depth
A/4L Section - 1/2" Width X 5/16" Depth
B/5L Section - 5/8" Width X 13/32" Depth
C Section - 7/8" Width X 17/32" Depth
D Section - 1-1/4" Width X 3/4" Depth
E Section - 1-1/2" Width X 29/32" Depth
AX Cogged Section - 1/2" Width X 5/16" Depth
BX Cogged Section - 5/8" Width X 13/32" Depth
CX Cogged Section - 7/8" Width X 17/32" Depth

Wedge V Belt Sections

3V Section - 3/8" Width X 21/64" Depth
5V Section - 5/8" Width X 35/64" Depth
8V Section - 1" Width X 7/8" Depth
3VX Cogged Section - 3/8" Width X 21/64" Depth
5VX Cogged Section - 5/8" Width X 35/64" Depth

How to determine the belt number

All A,B,C,D,E,AX,BX belts list the inside circumference measurement after the letter of the v belt part number. Example: A88 has a 88" inner circumference, then you add 2 inches for the A Section (Listed below) to obtain the outer circumference. If you measure the outer circumference, then you would subtract the number of inches based on the section you have (Listed below) to obtain the v belt number. This is also the same for the banded belts. Measure each individual band for banded belts to obtain the correct width.

Examples of how belt numbers are coded per section:

A Section= Add 2" to belt number (Example A88 = 90" Outside Circumference)
B Section= Add 3" to belt number (Example B88 = 91" Outside Circumference)
C Section= Add 4" to belt number (Example C88 = 92" Outside Circumference)
D Section= Add 5" to belt number (Example D105 = 110" Outside Circumference)
E Section= Add 6" to belt number (Example E144 = 150" Outside Circumference)
AX Section= Add 2" to belt number (Example AX60 = 62" Outside Circumference)
BX Section= Add 3" to belt number (Example BX50 = 53" Outside Circumference)

How fractional & wedge belt numbers are coded

All sections 3L,3V,5V,8V,3VX,5VX belts have the outside circumference after the number and letter(s). Example: Belt # 3V600 has a 60" outside circumference. Inside circumference are not measured for these sections. This is also for the banded belts. Measure each individual band for banded belts to obtain the correct width.

Examples of how belt numbers are coded per section:

3L Section= (Example 3L450 = 45" Outside Circumference)
3V Section= (Example 3V800 = 80" Outside Circumference)
5V Section= (Example 5V1180 = 118" Outside Circumference)
8V Section= (Example 8V2120 = 212" Outside Circumference)
3VX Section= (Example 3VX520 = 52" Outside Circumference)
5VX Section= (Example 5VX810 = 81" Outside Circumference)

Measuring K Micro Rib Belts:

Width's

K Section= 0.140" X's the number of ribs

All sections K micro rib belts will have the outside circumference in front of the letter. The rib count will be the number after the letter.

Outside Circumference & Rib Count per section:

K Section= (Example 845K8 = 84.5" Outside Circumference and 8 Ribs)

Measuring Belts