V Belt Size Chart and Cross Reference: A, B, C, 3V, 5V, SPZ

This v belt size chart decodes the stamp on a belt. The letter is the section; the number is the length, measured on a basis that depends on the family. The tables below cover classical, narrow, light-duty and metric wedge sizes.

Read the letter, then read the number on the correct length basis for that family. A worn belt or a bare code can still be matched once you know which length the number uses. Inch codes and metric codes do not follow one rule.

Jump straight to your family: classical A–E, narrow 3V/5V/8V, light-duty 3L/4L/5L, or metric SP.

Key Takeaways

• The letter names the section. The number names the length, and the basis depends on the family.
• North American classical codes state inside length in inches. Narrow and light-duty codes state outside length in tenths of an inch.
• Metric codes state datum length, which replaced the older inside length in the designation.
• The same section letter in the metric system and the inch system is not the same cross-section.
• A listed code is a designation, not a stock list. Match the section and the length basis before you order.

Table of Contents

• How to read a V belt size code
• Classical V belt sizes: A, B, C, D and E
• Narrow V belt sizes: 3V, 5V and 8V
• Light-duty 3L, 4L and 5L belt sizes
• Metric narrow belt sizes: SPZ, SPA, SPB and SPC
• V belt cross reference: matching sections and lengths
• How to measure a V belt when the code is unreadable
• When the size chart is not enough
• FAQ
• About Longyi Rubber Products Factory

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How to read a V belt size code

A V-belt code has two parts. The letter is the section, meaning the cross-section, and the number is the length.

A length can be stated three ways: inside, outside or datum. Datum length Ld is the basis ISO 4184 uses, and it replaced the older inside-length designation Li (Optibelt technical manual).

A100 is 100 in of inside circumference, 5V750 is 75.0 in of outside circumference, and 3L280 is 28.0 in of outside circumference (Turn2Engineering V-belt size chart). The table also reads SPB2000 as 2000 mm of datum length. Inch values in all tables are converted at 25.4 mm per inch (Inch on Wikipedia).

Sources: the Turn2Engineering size chart for the US series and the Optibelt technical manual for the ISO 4184 datum length.

Use the table before a length chart. For other profiles, see the types of V-belts.

Classical V belt sizes: A, B, C, D and E

Classical V belt sizes, also called vee belt sizes, are named by a section letter. The metric list and the North American list do not use the same dimensions. LYBELT lists these belts under classic V-belts.

ISO/DIN metric nominal sizes are Z 10 × 6, A 13 × 8, B 17 × 11, C 22 × 14, D 32 × 20 and E 38 × 23 mm (Turn2Engineering V-belt size chart).

Dimensions: catalog product dimensions as compiled in the Turn2Engineering size chart. Inch values are converted at 25.4 mm per inch.

North American nominal sizes are A 1/2 × 5/16, B 21/32 × 13/32, C 7/8 × 17/32, D 1-1/4 × 3/4 and E 1-1/2 × 29/32 in (Turn2Engineering V-belt size chart). Z is on the metric list only.

Dimensions: catalog nominal values as compiled in the Turn2Engineering size chart.

On a North American classical belt the number is the inside length in inches, and pitch length is that designation plus a section offset: A adds 1.3 in, B adds 1.8 in, C adds 2.9 in, D adds 3.3 in and E adds 4.5 in. A128 is 129.3 in pitch, B115 is 116.8 in, C109 is 111.9 in, D120 is 123.3 in and E180 is 184.5 in (Gates design manual).

The length tables show selected designations, and the same offsets apply to other designations in that size range. A listed code is not a stock list.

A section lengths

In the A length table, A38 is 38.0 in inside (965 mm) and 39.3 in pitch (998 mm) (Gates design manual). The same reading applies to A36, A39, A40, A48 and A49 belts: inside length plus the 1.3 in offset.

Pitch length = designation + 1.3 in for A-section belts, as in A128 = 129.3 in (Gates design manual).

B section lengths

In the selected table, a B60 V belt is 60.0 in inside (1524 mm) and 61.8 in pitch (1570 mm), because B adds 1.8 in (Gates design manual).

Pitch length = designation + 1.8 in for B-section belts, as in B115 = 116.8 in (Gates design manual).

C section lengths

C section pitch length is the inside-length designation plus 2.9 in (Gates design manual).

Pitch length = designation + 2.9 in for C-section belts, as in C109 = 111.9 in (Gates design manual).

D and E section lengths

D adds 3.3 in and E adds 4.5 in, so E180 is 184.5 in pitch (Gates design manual).

Pitch length = designation + 3.3 in for D-section belts, as in D120 = 123.3 in (Gates design manual).

Pitch length = designation + 4.5 in for E-section belts, as in E180 = 184.5 in (Gates design manual).

Narrow V belt sizes: 3V, 5V and 8V

Narrow sections are 3V, 5V and 8V. Nominal sizes are 3V 3/8 × 21/64, 5V 5/8 × 35/64 and 8V 1 × 7/8 in (Turn2Engineering V-belt size chart). The number is outside length in tenths of an inch, so 5V750 is 75.0 in outside (Turn2Engineering V-belt size chart). The narrow V-belts range uses these codes.

One manufacturer’s design manual lists sizes from 3V250 through 3V1400, from 5V500 through 5V3550, and from 8V1000 through 8V5600 (Gates design manual).

Dimensions: catalog nominal values as compiled in the Turn2Engineering size chart. Sizes offered run from 3V250 to 3V1400, 5V500 to 5V3550 and 8V1000 to 8V5600 in the Gates design manual.

3V belt lengths

3V codes run from 3V250 to 3V1400 in the design manual above; 3V475, for example, is 47.5 in of outside length.

The number is the outside length in tenths of an inch. Designations shown fall inside the size ranges in the Gates design manual.

5V belt lengths

5V750 means 75.0 in outside length, and that rule reads every 5V row (Turn2Engineering V-belt size chart).

The number is the outside length in tenths of an inch. Designations shown fall inside the size ranges in the Gates design manual.

8V belt lengths

8V is the biggest of the three sections, at 1 × 7/8 in, and its codes start at 8V1000.

The number is the outside length in tenths of an inch. Designations shown fall inside the size ranges in the Gates design manual.

Light-duty 3L, 4L and 5L belt sizes

Light-duty sections are 3L, 4L and 5L. Nominal sizes are 3L 3/8 × 7/32, 4L 1/2 × 5/16 and 5L 21/32 × 3/8 in (Turn2Engineering V-belt size chart). The number is outside length in tenths of an inch. A 4L and a North American A share the same 1/2 × 5/16 in nominal size, but 4L is a light-duty section and its number is the outside length, while an A number is the inside length.

Dimensions: catalog nominal values as compiled in the Turn2Engineering size chart.

The pattern is 3L280: 280 means 28.0 in outside length. The same rule reads a 3L200 as 20.0 in (508 mm), a 4L220 belt as 22.0 in (559 mm) and a 4L440 belt as 44.0 in (1118 mm) (Turn2Engineering V-belt size chart). These rows are not a stock list.

Rule: 3L280 means 28.0 in outside length, per the Turn2Engineering size chart; the other rows apply the same rule. These are decoding examples, not a stock list.

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Metric narrow belt sizes: SPZ, SPA, SPB and SPC

Metric narrow sections are SPZ, SPA, SPB and SPC. A finished-product set lists SPZ 9.7 × 8, SPA 12.7 × 10, SPB 16.3 × 13 and SPC 22 × 18 mm. A rounded nominal set lists 10 × 8, 13 × 10, 16 × 13 and 22 × 18 mm (Turn2Engineering V-belt size chart).

Both size sets come from the Turn2Engineering size chart, which lists the finished-product values and the rounded nominal values separately.

ISO 4184 designates these belts by datum length Ld, which replaced the former inside length Li (Optibelt technical manual). A stamp that reads spa 950, written SPA950, is a 950 mm datum length. The table converts that row to 37.4 in at 25.4 mm per inch.

Rule: ISO 4184 designates V-belts by datum length Ld, which replaced the older inside length Li (Optibelt technical manual). The number in a metric code is that length in millimeters. Inch values are converted at 25.4 mm per inch.

In a metric code the number is the datum length in millimeters. Do not add a classical pitch offset to an SP code.

V belt cross reference: matching sections and lengths

A V belt cross reference matches the family, the section and the length basis, not only the letter. Any belt equivalent chart has to state all three; the steps below work as a drive belt conversion chart between inch and metric codes.

Both size sets come from the Turn2Engineering size chart. The chart notes that an unqualified A or B is ambiguous across systems.

An unqualified A or B is ambiguous across systems. A dimensional match does not establish interchangeability, the correct length, the pulley groove or the duty (Turn2Engineering V-belt size chart).

Metric A is 13 × 8 mm. North American A on the comparison table is 12.7 × 7.9 mm (Turn2Engineering V-belt size chart). Same letter. Different size.

The closest US narrow and metric narrow sections differ in size too. US narrow nominal sizes are 3V 3/8 × 21/64 in (9.5 × 8.3 mm), 5V 5/8 × 35/64 in (15.9 × 13.9 mm) and 8V 1 × 7/8 in (25.4 × 22.2 mm) (Turn2Engineering V-belt size chart).

Metric narrow sizes are a finished-product set, SPZ 9.7 × 8, SPA 12.7 × 10, SPB 16.3 × 13 and SPC 22 × 18 mm, and a rounded nominal set, 10 × 8, 13 × 10, 16 × 13 and 22 × 18 mm (Turn2Engineering V-belt size chart). Two size sets. Not a pairing.

1. Name the family: classical inch, classical metric, US narrow, light duty or metric wedge.
2. Read the number as inside length, outside length or datum length.
3. Convert at 25.4 mm to the inch only after the basis is known. Do not add a classical offset to a narrow, light-duty or SP code.
4. Compare top width and height. The same letter isn’t the same belt.
5. Check the sheave groove and the length basis before you order.

PK and K profiles are ribbed belts, not in these V tables. For a ribbed belt cross reference, use the serpentine belt size chart, which lists serpentine belts by size.

How to measure a V belt when the code is unreadable

If the stamp is unreadable, measure the belt. Take top width and height with calipers and compare them with the section tables. The matching row is the section to test in the sheave.

Length is separate. Measure the path around the pulleys, or calculate it on the V-belt length calculation page. State the result as inside, outside or datum length.

A worn belt may no longer match its original size. Don’t treat the piece in your hand as the original designation.

When the size chart is not enough

Section and length fix the geometry. They do not fix the rubber. Heat, oil and load sit outside the chart.

Compound is a separate choice. Compare EPDM vs CR rubber belts when the exposure changes, and read about heat-resistant belts when heat is the constraint.

LYBELT works from 130+ rubber compounds and builds OEM and ODM belts to a customer’s code, drawing or size, with private label and packaging.

Send the code or a photo of the belt.

FAQ

The code on my old belt is worn off. Can I still match it?

Often, yes. Measure the top width and height and match a section table, then measure the pulley path or calculate the length and state it as inside, outside or datum length. Check the sheave groove before you order.

What does A38 mean on a V-belt?

A38 is an A-section belt with 38.0 in of inside length and 39.3 in of pitch length, which is the inside length plus the 1.3 in A-section offset (Gates design manual). The length table lists 965 mm inside and 998 mm pitch.

What is the difference between A and B section belts?

They are different cross-sections. Metric nominal sizes are 13 × 8 mm for A and 17 × 11 mm for B; North American nominal sizes are 1/2 × 5/16 in for A and 21/32 × 13/32 in for B (Turn2Engineering V-belt size chart).

How do I read a 5V750 or 3L280 belt code?

The 5V750 is a 5V belt with 75.0 in of outside length, and 3L280 is a 3L belt with 28.0 in of outside length (Turn2Engineering V-belt size chart). Both numbers are tenths of an inch.

Is an A section belt the same in the metric and inch systems?

No. Metric A is 13 × 8 mm and North American A is 1/2 × 5/16 in. The letters are not portable across systems, so check the section, the length basis and the pulley groove before ordering.

Which length does a V-belt code refer to: inside, pitch or outside?

It depends on the family: A100 is inside length, 5V750 and 3L280 are outside length, and a metric code is the datum length Ld (Optibelt technical manual).

Sources

1. Optibelt technical manual
2. Turn2Engineering V-belt size chart
3. Inch on Wikipedia
4. Gates design manual

Source names appear here only as references. LYBELT is not affiliated with them.

About Longyi Rubber Products Factory

LYBELT is the brand of Longyao County Longyi Rubber Products Factory (General Partnership), based in Longyao County, Xingtai, Hebei, China, and making rubber belts since 1999. The factory holds IATF 16949 and ISO 9001 certification and works from 130+ rubber compounds.

The range covers automotive, industrial, agricultural, ATV/UTV and motorcycle belts. For OEM and ODM orders, belts are made to the customer’s part number, drawing or size, with private label and packaging. Email: luxin@lybelt.com.

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