How to use the fence setting
The answer is the distance from the fence to the nearest blade tooth at table level. Tilt the blade to 45° away from the fence, then place the keeper piece between the blade and fence. The calculator's fence setting is also the short-face width of that cleat. The other half is the offcut and becomes the matching cleat when one piece is flipped.
Check your saw's manual before making a bevel rip. The workpiece must be supported and the fence, guard, riving knife and push equipment must suit the cut and your machine.
Why the kerf is wider at 45 degrees
Blade kerf is measured perpendicular to the blade. When the blade passes through a flat board at 45°, that kerf spans a greater distance across the board face. The calculator uses blade kerf ÷ cos(45°), which is the same as multiplying the blade kerf by approximately 1.414.
For a 2.4 mm blade, the kerf across the board face is about 3.4 mm. Ignoring that extra width shifts both cleats and can leave the result noticeably different from the intended equal split.
Worked example: 150 × 18 mm board
Start with a board 150 mm wide and 18 mm thick, using a blade with a 2.4 mm kerf. The projected face kerf is 3.4 mm. The short face is therefore(150 - 18 - 3.4) ÷ 2 = 64.3 mm. The long face is the short face plus the board thickness: 64.3 + 18 = 82.3 mm. Set the fence to 64.3 mm using the nearest tooth at table height as the blade reference.
Measure the material before cutting
Nominal sheet thickness is often not the thickness in your workshop. An 18 mm plywood sheet may measure 17.5 mm, and that difference changes the fence setting. Measure the actual board with calipers and use the blade manufacturer's kerf or, better, a kerf you have verified from a test cut.
Also check that the blade is truly at 45°, rather than relying only on the saw's detent. Make a test cut, flip one half and bring the bevels together. They should mate without a gap. Read the broader safety and limitations guidance before treating any generated dimension as a final workshop instruction.
Common questions
Does this make two equal-width French cleats?
It makes two congruent cleats from one board. Each piece has the same short face and the same long face after one is turned around. The long face is wider than the short face by exactly the board thickness because the cut is fixed at 45°.
Should the blade lean towards or away from the fence?
This fence number assumes the blade tilts away from the fence and the keeper piece runs between the fence and blade. If your machine or safe setup requires another arrangement, do not transfer the number blindly; establish the correct measuring reference with a test piece.
Can I use this for a different bevel angle?
No. This is intentionally a French-cleat task calculator and assumes a true 45° cut. Different angles change both the horizontal offset and the projected kerf, and the two halves no longer describe this standard matching-cleat setup.