How do I measure a V-belt length?

Measure the outside circumference by wrapping a flexible tape measure around the outer edge of the belt. This gives you the outside length (OC). For example, a belt measuring 35 inches around the outside is typically labeled as a _350 belt.

How do I determine V-belt width?

Measure across the top (widest) surface of the belt. Common widths: 3/8" (3L), 1/2" (4L/A), 21/32" (5L/B), 7/8" (C). The width determines the belt type/section.

What do V-belt numbers mean?

The letters indicate belt type/width (4L, 5L, A, B, etc.) and the numbers indicate length. For example, 4L350 means a 4L type belt with 35.0 inch outside length.

How to Measure a V-Belt - Complete Guide with Diagrams

How to Measure a V-Belt

Need to find a replacement V-belt but don't have the part number? This guide shows you how to measure and identify any V-belt using simple tools.

What You'll Need

Flexible tape measure or string + ruler
Calipers or ruler (for width/depth)
The old belt (if available)

Step 1: Measure the Width (Top Width)

Measure across the top surface of the belt - the widest part that faces outward when installed.

Top Width	Belt Type
3/8" (9.5mm)	3L
1/2" (12.7mm)	4L or A or AX
21/32" (16.7mm)	5L or B or BX
7/8" (22.2mm)	C or CX

Step 2: Measure the Length

V-belts are measured by outside length (outside circumference):

Lay the belt flat
Wrap a flexible tape measure around the outer edge
Read the total circumference

Example: If the outside measures 35 inches, you have a _350 belt (35.0")

No Belt Available?

If you don't have the old belt, measure the pulley centers and calculate:

Outside Length ≈ 2 × (center distance) + 1.57 × (pulley diameters)

Or contact us with your equipment model for the correct belt specification.

Step 3: Check for Special Features

Notches on bottom? → Cogged belt (AX, BX, CX)
Yellow/tan colored cords? → Kevlar reinforced (K suffix)
Multiple belts joined? → Banded/joined belt

Understanding V-Belt Part Numbers

Part numbers follow a simple pattern:

4L350K

↑ Type   ↑ Length (35.0")   ↑ Kevlar (optional)

V-Belt Size Chart

Type	Width	Depth	Common Uses
3L	3/8"	7/32"	Small motors, light duty
4L / A	1/2"	5/16"	Lawn mowers, light equipment
5L / B	21/32"	7/16"	Riding mowers, snow blowers
C	7/8"	17/32"	Industrial, heavy equipment

Need Help?

Can't identify your belt? Contact us with your equipment make/model and we'll find the right belt for you.

Shop All V-Belts →

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