A cabinet door that is 1/16″ too wide will not close — and one that is 1/16″ too narrow shows a gap you will see every day. Enter your cabinet opening below and this calculator works out the exact finished door size, the length to cut your stiles and rails, the panel size, and how many hinges you need.
Your cabinet opening
How the math works
For an overlay door, the door is bigger than the opening by the overlay on every side:
Door width = opening width + 2 × overlay · Door height = opening height + 2 × overlay
For an inset door the logic flips — the door sits inside the opening, so you subtract the reveal gap on each side:
Door width = opening width − 2 × reveal · Door height = opening height − 2 × reveal
Then the frame parts follow from the finished door size. Each stile runs the full height of the door. Each rail fits between the stiles with a stub tenon in the groove, and the panel floats in the groove with room to expand:
- Stile length = door height (×2)
- Rail length = door width − 2 × stile width + 2 × groove depth (×2)
- Panel width = door width − 2 × stile width + 2 × groove depth − 2 × allowance
- Panel height = door height − 2 × rail width + 2 × groove depth − 2 × allowance
Worked example: opening 18″ × 30″, full overlay 0.5″, stiles and rails 2.5″, groove 0.375″, allowance 0.125″. Door = 19″ × 31″. Stiles: 31″ (×2). Rails: 19 − 5 + 0.75 = 14.75″ (×2). Panel: 19 − 5 + 0.75 − 0.25 = 14.50″ wide and 31 − 5 + 0.75 − 0.25 = 26.50″ high. At 31″ tall the door needs 3 hinges.
Tips before you cut
- Measure the opening twice, in two places. Cabinet openings are rarely perfectly square — use the smallest width and height you measure.
- Test the overlay on scrap first. A 1/2″ overlay is the standard for frameless cabinets, but check your hinge’s adjustment range before committing.
- Never glue the panel. The panel must float in its groove so it can expand and contract with the seasons — glue it and the door will crack.
- Learn the joints behind the door. Our guide to woodworking joinery types for beginners explains the stub tenon and groove joint this door relies on.
Frequently asked questions
What is the difference between overlay and inset cabinet doors?
An overlay door sits on top of the cabinet frame and covers part (partial overlay) or almost all (full overlay) of the face frame. An inset door sits flush inside the opening, with a small even reveal gap around all four edges. Overlay is more forgiving to build; inset looks more refined but demands tighter measurements.
How wide should cabinet door stiles be?
2″ to 2.5″ is the standard for most kitchen and built-in cabinet doors — wide enough for a solid joint and a comfortable grip, narrow enough to keep the panel the star. Very tall doors (over 48″) can go to 3″ stiles for extra stiffness.
Why does the panel float instead of being glued in?
Wood moves across the grain as humidity changes. A glued-in panel has nowhere to go, so either the panel or the frame cracks. The groove plus a small expansion allowance (about 1/8″ per edge) lets the panel swell and shrink freely while staying trapped in the frame.
How many hinges does a cabinet door need?
Two hinges for doors up to 30″ tall, three hinges for doors from 30″ to 48″, and four hinges for anything taller than 48″. Heavier doors — thick hardwood or a mirror panel — should go up one hinge count.