Use the most reliable source available: check the machine manual or nameplate first, then a correctly fitted old blade. Use wheel measurements only to estimate the length of a conventional two-wheel saw. Always verify length, width, thickness, and permitted tension range before ordering.
1. Read the machine nameplate and manual
Look for a plate near the motor, electrical enclosure, upper wheel housing, rear cover, or base. The owner’s manual or parts list may contain the blade specification even when the plate does not.
Record these identity fields
- Manufacturer
- The company that made the saw
- Model
- The exact model, including letters, numbers, and type or series
- Serial or type number
- Useful when one model changed specification between production runs
- Machine category
- Portable, woodworking, butcher, vertical metal, or horizontal production saw
Record these blade fields
- Blade length
- The closed-loop length, often shown in millimetres or inches
- Blade width
- From the tooth tip to the back edge
- Blade thickness
- The gauge of the blade body
- Permitted width range
- Common on woodworking saws that accept narrow and wide blades
- Speed range
- Helps confirm application and blade construction after size is known
Portable bandsaws need an exact model match
Compact, sub-compact, deep-cut, and cordless portable bandsaws can look similar while using different loop lengths. Use the complete model and type number to check the manufacturer’s manual or approved accessory list. Do not infer blade length from cutting capacity or measure the outside of the housing. Portable saws may use closely spaced nominal sizes that are not interchangeable.
Woodworking bandsaws need size and width range
For a woodworking bandsaw, confirm the loop length and the minimum and maximum blade width allowed by the manufacturer. Width is then chosen for the job: narrower blades can follow tighter curves, while wider blades generally provide more support for straight cuts and resawing when the machine permits them. Thickness must remain suitable for the wheels and guides.
2. Measure a correctly fitted old blade
Only use an old blade as the reference when you know it fitted and tensioned correctly. Isolate the machine and follow its blade-removal instructions. Wear suitable hand and eye protection; large loops can spring open and should be handled by trained personnel.
Measure the loop length
- Place the uncoiled loop on a clear floor or long workbench without twisting it.
- Mark one reference point on the blade back and the matching start point on the surface.
- Roll the loop carefully along its back edge for one complete revolution until the blade mark returns to the surface.
- Measure the distance between the start and finish points. Repeat the measurement to check consistency.
Do not measure around a folded coil and do not assume the old blade is correct if the machine could not tension or track it normally.
Measure the rest of the specification
| Field | How to measure or identify it | Common mistake |
|---|---|---|
| Width | Measure from the tooth tip to the back edge | Measuring only the blade body below the teeth |
| Thickness | Use a micrometer on clean blade body away from the weld and tooth set | Measuring across a set tooth or burr |
| TPI | Count tooth spacing over one inch, or record both values of a variable pitch | Assuming TPI from length or machine model |
| Tooth direction | Photograph the blade as installed before removal | Installing the replacement with teeth facing away from the cutting direction |
3. Two-wheel bandsaw blade length estimator
Use this only when the manual, nameplate, and correct old blade are unavailable. It estimates the open-loop path around two wheels. Place the adjustable wheel near the middle of its tension travel before measuring center distance.
Estimated reference length
This is an estimate, not an ordering confirmation. Tyre thickness, blade tracking position, wheel geometry, measuring error, and tension travel can change the required production length.
Formula and assumptions
For wheel diameters D1 and D2, with center distance C, the estimator uses:
L ≈ 2C + π(D1 + D2) ÷ 2 + (D1 − D2)² ÷ 4C
For two equal wheels of diameter D, this simplifies to L ≈ 2C + πD. The formula approximates an open belt path and assumes two circular wheels in the same plane. It is not suitable for three-wheel saws, twisted blade paths, portable saw internals, or machines with additional routing pulleys.
Before ordering the replacement
- Confirm the manufacturer, full model, and type or serial range.
- Confirm length, width, and thickness as separate values.
- Check that the estimated length sits within the machine’s tension adjustment range.
- Choose tooth pitch only after identifying the material and workpiece section.
- For portable and three-wheel saws, use the manufacturer’s specified blade size.
- Send photos and measurements when any value remains uncertain.