How to Read a Hose Clamp Size Chart
How to Read a Hose Clamp Size Chart
Hose clamp size charts can be confusing if you don't know what the numbers mean. Here's a simple guide to reading clamp specs and finding the right size for your hose.
What the Numbers on a Hose Clamp Mean
- Diameter range (min–max): The range of hose outer diameters the clamp can accommodate. A clamp listed as 5/8"–1-1/16" can clamp any hose OD between those two measurements.
- Band width: Typically 1/2" or 9/16" for standard worm gear clamps. Wider bands are better for soft hoses.
How to Measure Your Hose
- Use calipers or a tape measure to measure the outer diameter (OD) of the hose — not the inner diameter.
- If the hose is already on a fitting, measure the OD over the fitting.
- Choose a clamp whose diameter range includes your measurement, ideally near the middle of the range.
Pro tip: Don't choose a clamp at the very top or bottom of its range — less thread engagement means reduced clamping force.
Standard Worm Gear Clamp Size Chart
| Clamp Size | Diameter Range (inches) | Diameter Range (mm) |
|---|---|---|
| #4 | 3/16" – 5/8" | 5 – 16 mm |
| #6 | 5/16" – 7/8" | 8 – 22 mm |
| #8 | 7/16" – 1" | 11 – 25 mm |
| #10 | 5/8" – 1-1/16" | 16 – 27 mm |
| #12 | 11/16" – 1-1/4" | 17 – 32 mm |
| #16 | 13/16" – 1-1/2" | 21 – 38 mm |
| #20 | 1" – 2" | 25 – 51 mm |
| #24 | 1-5/16" – 2-1/4" | 33 – 57 mm |
| #28 | 1-9/16" – 2-1/2" | 40 – 64 mm |
| #32 | 1-13/16" – 3" | 46 – 76 mm |
| #40 | 2-1/16" – 3-1/2" | 52 – 89 mm |
| #48 | 2-9/16" – 4-1/2" | 65 – 114 mm |
| #56 | 3-1/16" – 5" | 78 – 127 mm |
| #64 | 3-9/16" – 5-1/2" | 90 – 140 mm |
Clamp Types and When to Use Each
- Worm gear clamps — adjustable, reusable, good for most applications.
- Spring clamps — OEM-style, constant pressure, must match hose OD exactly.
- T-bolt clamps — heavy-duty for high-pressure and high-vibration applications.
- Ear clamps (Oetiker-style) — single-use, crimped with a special tool, common in OEM fuel and coolant lines.
Common Mistakes When Sizing Hose Clamps
- Measuring the hose ID instead of OD — always measure the outside.
- Choosing a clamp at the extreme of its range — pick one where your OD falls in the middle third.
- Using a clamp that's too narrow — use a wider band on silicone or rubber hoses.
- Overtightening — tighten until snug and sealed, then stop.
Shop Hose Clamps at Chem Nut Supply
Chem Nut Supply carries a full selection of worm gear hose clamps, T-bolt clamps, and hose clamp assortment kits. Shop our Hose Clamps collection to find the right clamp for your application.