How to use this calculator
- Enter outside frame size. Use the finished outside face-frame width and height.
- Set outside rails and stiles. Enter left/right stile width and top/bottom rail width.
- Add dividers. Enter intermediate vertical and horizontal divider counts and widths.
- Read clear openings. Use the opening width and height for door, drawer or shelf follow-up calculators.
How it works
Face-frame opening layout starts from the outside frame size. The calculator subtracts the outside stiles and any intermediate vertical dividers, then splits the remaining width across the column count. opening width = (frame width - left stile - right stile - divider widths) / columns
Height is handled the same way with rails and horizontal dividers: opening height = (frame height - top rail - bottom rail - divider widths) / rows The stock length screen assumes outside stiles are full height, rails run between outside stiles, and vertical dividers run between top and bottom rails.
After the openings are known, use the cabinet door size calculator for overlay or inset doors, the drawer box size calculator for drawer openings, and the cut list calculator to turn rails and stiles into stock cuts with kerf and waste.
Worked example
Verified against the live calculator
A face frame is 36 in wide and 30 in tall, with
1-1/2 in left and right stiles, 1-1/2 in top and
bottom rails, and one 1-1/2 in center stile. The two opening
columns are (36 - 1.5 - 1.5 - 1.5) / 2 = 15.75 in wide. With
no horizontal divider, the opening height is 30 - 1.5 - 1.5 = 27 in.
Frequently asked questions
How do you calculate a cabinet face-frame opening?
Subtract the left and right stile widths plus any vertical divider widths from the outside frame width, then divide by the number of columns. Subtract the top and bottom rail widths plus any horizontal divider widths from the outside height, then divide by the number of rows.
Does this calculate cabinet door size too?
No. This calculator finds the clear face-frame openings. Use the cabinet door size calculator after this step to add overlay or subtract inset reveals.
Are rail and stile tenons included?
No. The stock length output uses a simple layout convention before tenons, pocket holes, cope-and-stick details, scribe strips or shop-specific waste.
Can I use this for drawer openings?
Yes. It gives the clear face-frame opening. Use the drawer box size calculator after that to subtract slide clearances and cabinet depth setbacks.
Method & assumptions
- Inputs are finished rectangular face-frame dimensions, not cabinet case dimensions unless those match the outside frame.
- Columns equal vertical dividers plus one; rows equal horizontal dividers plus one.
- Rail length is treated as the distance between outside stiles. Vertical divider length is treated as the distance between top and bottom rails.
- Does not include tenons, pocket holes, cope-and-stick joinery, scribe strips, fillers, hinge boring, door overlays, inset reveals, drawer slide clearances or out-of-square correction.