- Material used
- 98.4%
- Layout waste
- 1.6%
Kerf calculator
Will blade width cost you another sheet?
Compare the impossible zero-width cut with the space your real blade removes. The difference is often invisible until a tight row no longer fits.
Interactive comparison
See what the blade removes from the plan.
Run the same rectangular parts twice—once with a zero-width cut and once with your real blade kerf—to expose the difference.
- Material used
- 49.2%
- Layout waste
- 50.8%
Kerf adds 1 sheet to this layout.
The zero-kerf grid only fits on paper; the real blade needs space between adjacent parts.
The practical rule
Finished size stays fixed. Clearance belongs between parts.
n parts in one rown × part width + (n − 1) × kerf
Four 600 mm parts need exactly 2400 mm with zero kerf. With a 3.2 mm blade, the three gaps raise that row to 2409.6 mm before margins.
Measure the real cutter
Use a test cut in the same material. Nominal blade width and actual removed width can differ.
Keep margin separate
Kerf separates cuts. Outside margin protects the sheet edge and should be entered independently.
Compare before buying
Run the layout before ordering stock; sheet-count changes are more expensive than small yield changes.
Shop measurement
Measure actual kerf with the tool, setup, and material you will use.
The number printed on a blade or bit is a starting point, not a guarantee of the slot left in a particular sheet. Tooth set, runout, feed, material behavior, and machine setup can change the removed width. A short test makes the calculator reflect the real cutting system instead of a catalogue dimension.
- Prepare a representative offcut.
Use the same material and thickness as the job. Install the blade or bit, set the normal speed and feed, and make one straight test cut with the setup fully secured.
- Measure the cut, not the finished part.
Measure the width of the removed slot with an appropriate gauge or caliper. If the slot is awkward to reach, make two reference marks, cut between them, and compare the remaining pieces with the original span.
- Repeat before trusting the value.
Take several readings along the test path and repeat the cut when they disagree. Variation can reveal blade deflection, vibration, material breakout, or a measurement method that is not precise enough for the job.
- Enter a truthful planning value.
Use the repeatable removed width rather than enlarging every finished part. Recheck after changing the cutter, material, machine setup, or any condition that could alter the cut.
Why a small kerf can have a large layout effect
Kerf accumulates at every required separation. In a row of n parts, there are normally n − 1 internal gaps, before any outside margin is added. A layout with generous spare space may keep the same sheet count and only lose a little yield. A tightly filled row can cross the usable boundary after just a few accumulated gaps, moving one or more parts to another sheet. That is why the useful comparison is the completed layout with and without measured kerf—not the blade width viewed in isolation. Test both a comfortable layout and the tightest likely production case: the first shows the ordinary yield change, while the second reveals whether accumulated clearance changes the required stock count. Record the measured setup with the estimate so another cutter is not assumed to behave identically.
Questions
Kerf calculator FAQ
What is kerf in cutting?
Kerf is the width of material removed by a saw blade, router bit, laser, or other cutting tool. A 3.2 mm blade removes a 3.2 mm-wide path from the sheet.
Do I add kerf to every part dimension?
Keep the finished part dimensions unchanged. The layout planner should reserve kerf between adjacent cuts instead of enlarging the part itself.
Why can a small kerf require another sheet?
A tight zero-kerf grid may exactly fill the stock. Once every neighboring part needs blade clearance, the final row or column can cross the usable sheet boundary.
Does this calculator produce a cut sequence?
This page compares kerf-aware Free Nesting layouts. Use Guillotine Cutting in the full optimizer when you need a through-cut sequence and cut-length metrics.
Ready for the complete cut list?
Add mixed parts, margins, rotation, and compare Free Nesting with a real Guillotine cut sequence.