How to Measure a V-Belt: A Simple Guide for Getting the Right Fit

How to Measure a V-Belt: A Simple Guide for Getting the Right Fit

Whether you're replacing a worn-out belt or cross-referencing a part number, knowing how to properly measure a V-belt can save you time, frustration, and money. The right fit keeps your equipment running smoothly—while the wrong one can cause slipping, overheating, or even costly breakdowns.

Here’s everything you need to know to accurately measure a V-belt, even if the original part number is missing.

What You’ll Need:

  • A flexible measuring tape or cloth tape measure
  • A flat surface
  • The old belt (if available)
  • Optional: a piece of string and a ruler

Step 1: Identify the Type of V-Belt

Before you measure, it’s helpful to know which kind of V-belt you’re dealing with:

Classic, Kevlar, & FHP V-Belts

  • 2L Section – 1/4" Width x 5/32" Depth
  • 3L Section – 3/8" Width x 7/32" Depth
  • A / 4L Section – 1/2" Width x 5/16" Depth
  • B / 5L Section – 21/32" 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

Wedge V-Belts

  • 3V Section – 3/8" Width x 5/16" Depth
  • 5V Section – 5/8" Width x 17/32" Depth
  • 8V Section – 1" Width x 7/8" Depth

Cogged (Notched) V-Belts

  • AX Section – 1/2" Width x 5/16" Depth
  • BX Section – 21/32" Width x 13/32" Depth
  • CX Section – 7/8" Width x 17/32" Depth
  • 3VX Section – 3/8" Width x 5/16" Depth
  • 5VX Section – 5/8" Width x 17/32" Depth
  • 8VX Section – 1" Width x 7/8" Depth

Knowing the type helps determine how and where to measure the belt.

Step 2: Measure the Outside Circumference

If you still have the old belt:

  1. Lay the belt flat on a table in its natural loop.
  2. Use your measuring tape to measure the outside diameter (OD) of the belt.
  3. If the belt is broken or cut, lay it flat and measure the entire length from end to end.

Tip: You can also use a string to wrap around the pulleys as a substitute for a belt, and then measure that string to estimate the belt length.

Step 3: Measure the Width and Height

Use calipers or a ruler to measure:

  • Top Width (Outside Width): Measure across the widest part of the belt.
  • Thickness (Height): Measure from the bottom to the top of the belt.

These dimensions will help match your belt to the correct cross-section (A, B, C, etc.).

Step 4: Cross-Reference Your Measurement

Once you’ve got the measurements, compare them with a V-belt size chart or use an online cross-reference tool. Manufacturers often list both inside and outside lengths, so make sure you're comparing the right one.

Final Tips:

  • V-belts are sized by their effective length (not just outer length), so using manufacturer part numbers when possible is ideal.
  • If your machine uses multiple belts side by side, always replace all belts at once for even wear and tension.
  • Mark down the part number once you find the right belt—it’ll save you a step next time.

Need Help Finding the Right V-Belt?

At V-Belt Nation, we make it easy to search by size, OEM number, or application. Our team is happy to help you identify the right belt—just send us your measurements, OEM part number, and/or serial number!

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