Start with the actual project
Cut a test slot and tab, measure both after cooling, then adjust the measured full kerf rather than guessing a machine-wide constant.
Write down each measurement with its unit. Enter lengths in the displayed unit and keep counts separate from dimensions. If a product specification provides a value, use that value for the exact material or equipment involved.
| Measurement | Unit | Example |
|---|---|---|
| Target finished tab width or measured sheet thickness | mm | 3 |
| Full kerf width | mm | 0.15 |
| Total clearance | mm | 0.05 |
Work through the calculation
- Open the calculator and replace every example input that differs from your project.
- Read the named results and their units. A negative remaining-space result describes a fit problem, not a usable dimension.
- Save a baseline before changing assumptions. Adjust one measurement at a time to see what drives the result.
- Use the comparison table and the exact values beneath the chart to check the effect of a change.
- Export a worksheet or print the final result, then verify a sample before making an irreversible cut or purchase.
Project-specific checks
- A centerline cut removes half the kerf on each side. An internal opening grows by one full kerf; an external tab shrinks by one kerf.
- Clearance here is total width clearance, not clearance per side. A 0.10 mm total clearance means 0.05 mm on each side when centered.
- If your laser software already applies kerf compensation, use the target finished size there instead of compensating twice.
- Test a small comb on the same sheet, grain direction, lens setting and cut speed before committing the full sheet.
Read rounding correctly
Whole-item counts may round upward to cover a requirement or downward to fit a space. The formula reference identifies ceil and floor operations. Displayed decimals are rounded for readability; calculations keep the underlying numeric precision.
When a number looks wrong
First check units and inside-versus-outside dimensions. Next check whether allowances were included twice. Finally compare the input assumptions with the project-specific checks above. The worked scenarios provide a reproducible starting point.
Open the calculator