Kerf belongs between finished parts
If two finished parts sit next to each other on one board, the cut between them removes material. A plan that simply adds finished lengths can therefore overstate how many parts fit. Enter one measured or manufacturer-confirmed kerf for each continuing cut channel in the planning method you use.
Do not assume that a circular saw or table saw blade's printed plate width, tooth width and finished kerf are interchangeable. Blade condition, tooth set, run-out, material and machine setup can affect the actual cut. A test cut in comparable scrap gives a better job-specific check than a generic internet number.
A simple repeated-cut example
Four 500 mm finished pieces total 2000 mm. If the sequence needs three separating cuts at an entered 3.2 mm kerf, those channels consume another 9.6 mm before end trim or defects. The arithmetic is simple; deciding how many kerf channels the chosen sequence creates is the important part.
The cut list optimiser includes the entered kerf when it splits the remaining rectangles. Its result is still a placement plan, not a prescribed cutting order.
When not to reuse one kerf value
- Different blades or tools are used in the same job.
- A rough breakdown cut is followed by a separate finishing cut.
- Parts are planed, jointed or trimmed after sawing.
- A patterned face or veneer requires a visible matching gap.
- The stock is already edged or damaged.
In those cases, enlarge the blank dimensions or split the plan into stages rather than pretending one kerf field describes every operation.
Machine safety remains separate
HSE woodworking guidance covers guarding, braking, extraction, push sticks and safe systems of work for woodworking machinery. This guide does not replace machine instructions, training or a task risk assessment. See the sources page for the cited HSE circular-saw guidance.