French Cleat Calculator: 45° Rip Sizes, Screws, Studs and Safe Load
Design a French cleat for cabinets, tool walls or heavy mirrors: the two cleat sizes from a 45° rip, how many studs or anchors the wall cleat catches, screw length through the drywall, a conservative safe-load check, the lift needed to unhook, the bottom spacer and cleat-wall spacing.
How it works
kerf across the face = kerf × √2; long face = (W + T − kerf√2) ÷ 2, short face = (W − T − kerf√2) ÷ 2; bevel = T × √2; studs caught = ⌊(L − 50 mm) ÷ spacing⌋ + 1; safe load = fixings × load per fixing (aim ≥ 1.5 × weight); screw = cleat + wall board + 38 mm in the stud; lift to unhook ≈ T + 6 mm; cleat-wall pitch ≈ 2 × long face + 20 mm
A French cleat is a board ripped in two along a 45° bevel. One half is screwed to the wall with its bevel facing up and toward the wall, forming a pocket. The other half goes on the back of the object with its bevel facing down, so it drops into the pocket. Gravity wedges the two together and pulls the object tight to the wall. Because the cut runs diagonally through the thickness, each piece ends up with a long face and a short face that differ by the board thickness. The saw also removes about 1.4 times its kerf from the width. The wooden joint is very strong, so the real limit is how the wall cleat is fixed. The calculator counts how many studs a cleat of your length can catch (or how many anchors fit), multiplies by a conservative safe load per fixing and compares it with the weight, aiming for at least a 1.5× margin. Screws must pass through the cleat and the drywall and still bite about 38 mm (1½″) into the stud, which is why the drywall thickness matters. To take the object off, you lift it by about the cleat thickness so the hanging cleat clears the top of the wall cleat. Leave that much space above it. A spacer strip of the same thickness at the bottom keeps the object plumb. For a tool wall, repeat the wall cleats at a steady pitch so any holder fits anywhere.
Worked example
Ripping an 89 × 19 mm board at 45° with a 3.2 mm kerf removes 3.2 × √2 = 4.53 mm. Each cleat is (89 + 19 − 4.53) ÷ 2 = 51.7 mm on its long face and (89 − 19 − 4.53) ÷ 2 = 32.7 mm on its short face, with a 26.9 mm bevel. A 900 mm wall cleat on studs at 406 mm can catch ⌊(900 − 50) ÷ 406⌋ + 1 = 3 studs. At 35 kg per screw that is 105 kg of safe load, 1.75× a 60 kg cabinet, so it is OK. Through 12.5 mm drywall each screw needs 19 + 12.5 + 38 = 69.5 mm, so use 70 mm (2 3/4″) screws. You need 25 mm of lift to unhook the cabinet and a 19 mm spacer strip at its base.
Sources: French cleat (Wikipedia)
Frequently asked questions
How much weight can a French cleat hold?
The wooden cleat itself can carry hundreds of kilograms; the fixings into the wall set the limit. As a conservative guide, allow about 35 kg (75 lb) per screw into a stud, 40 kg per masonry anchor and 12 kg per drywall toggle, and keep at least a 1.5× margin. A 900 mm cleat across three studs safely carries about 100 kg.
What angle should a French cleat be?
45° is standard. It pulls the object tight to the wall and is easy to lift off. Steeper angles (around 30° from vertical) lock tighter but are harder to remove; shallow angles can let the object slide out.
How long should the screws be for a French cleat?
Long enough to pass through the cleat and the drywall and still go about 38 mm (1½″) into the stud. For a 19 mm cleat on 12.5 mm drywall that is about 70 mm (2¾″). Use #8–#10 (4–5 mm) construction screws.
Plywood or solid wood for French cleats?
Plywood (18–19 mm, ¾″) is the usual choice: it does not split along the bevel and stays flat. Solid hardwood works for furniture-grade cleats. Avoid MDF, whose bevel edge crumbles.
How far apart should French cleats be on a tool wall?
At least two cleat faces plus a small gap, so the cleat on the back of a holder clears the one below. With cleats ripped from a 1×4 that is about 120–125 mm. Many people use 150–200 mm (6–8″) so larger holders fit.
Related calculators
Woodworking rules of thumb and conservative fixing estimates. Check your wall construction, use the fastener maker’s rated loads, and get professional advice for very heavy or overhead items.