What are the dimensions of a 4L belt?

A 4L belt has a top width of 1/2 inch (12.7mm) and a depth of 5/16 inch (7.9mm) with a 40° V-angle. These are Fractional Horsepower (FHP) belts designed for light-duty applications.

What is a 4L belt used for?

4L belts are commonly used in lawn mowers, garden equipment, small compressors, light-duty fans, HVAC systems, and household appliances. They're ideal for applications requiring up to 1-2 horsepower.

What does the number in a 4L belt mean?

The number after '4L' indicates the belt's outside length in inches. For example, a 4L350 belt is 35.0 inches in outside circumference. A 4L420 would be 42.0 inches long.

What is the difference between a 4L and an A belt?

4L and A belts have the same cross-section dimensions (1/2" x 5/16"). The difference is construction: 4L belts are light-duty FHP (Fractional Horsepower) belts for smaller equipment, while A belts are industrial-grade with heavier construction for longer service life in demanding applications.

Can I use a 4L belt instead of an A belt?

Yes, 4L and A belts are dimensionally interchangeable since they share the same width and depth. However, for heavy-duty or continuous industrial use, an A belt will typically last longer. For lawn equipment and light-duty applications, a 4L belt works well.

4L Belt Guide - Dimensions, Sizes & Applications

4L V-Belt Guide: Dimensions, Sizes & Applications

The 4L belt is one of the most common V-belt types, found in lawn mowers, garden equipment, and light-duty machinery across America. This guide covers everything you need to know about 4L belts - dimensions, sizing, applications, and how to find the right replacement.

4L Belt Dimensions

All 4L belts share the same cross-sectional dimensions:

Specification	Value
Top Width	1/2" (12.7mm)
Depth (Height)	5/16" (7.9mm)
V-Angle	40°
Belt Type	FHP (Fractional Horsepower)
Min. Pulley Diameter	2.5" (3" recommended)

Understanding 4L Belt Part Numbers

4L belt part numbers tell you the belt's outside length. The format is simple:

4L350 = 4L belt, 35.0" outside length

More examples:

4L200 = 20.0" outside length
4L350 = 35.0" outside length
4L460 = 46.0" outside length
4L550 = 55.0" outside length

What Does the "K" Suffix Mean?

A "K" at the end (like 4L350K) indicates a Kevlar-reinforced belt. Kevlar belts offer:

2-3x longer service life
Better heat resistance
Less stretch over time
Ideal for demanding applications or hard-to-access locations

Learn more about Kevlar vs Standard belts →

Common 4L Belt Applications

4L belts are the workhorse of lawn and garden equipment:

Walk-behind lawn mowers - blade and drive belts
Riding mower decks - smaller deck sizes
Garden tillers - tine drive
Snow blowers - auger and drive systems
Air compressors - small shop compressors
HVAC equipment - blower motors, fans
Household appliances - washing machines, dryers
Exercise equipment - treadmills, stationary bikes

4L vs A Belt: What's the Difference?

This is one of the most common questions we get. Here's the answer:

Feature	4L Belt	A Belt
Top Width	1/2" (12.7mm)	1/2" (12.7mm)
Depth	5/16" (7.9mm)	5/16" (7.9mm)
Construction	Light-duty FHP	Industrial-grade
Best For	Lawn equipment, light use	Industrial, continuous duty
Interchangeable?	Yes - same dimensions

Bottom line: 4L and A belts fit the same pulleys. Use 4L for lawn equipment and light duty; use A for industrial applications where longevity matters.

How to Measure for a 4L Belt

If you don't know your belt size, measure it:

Confirm the width - Should be 1/2" across the top
Measure outside length - Wrap a tape measure around the outer edge of the belt
Find the part number - Divide the length by 10 and add "4L" prefix

Example: Belt measures 35" around the outside → 4L350

Complete belt measuring guide →

Shop 4L Belts

We stock 185 4L belt sizes in both standard and Kevlar versions, ready to ship.

Shop All 4L Belts →

Popular 4L Belt Sizes

Finding OEM Cross-References

Looking for a 4L belt to replace an OEM part number? Many equipment manufacturers use proprietary part numbers for standard 4L belts. Check our cross-reference guides:

Need Help?

Not sure which 4L belt you need? Contact us with your equipment make and model, and we'll help you find the right belt.

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