For one overlay cabinet door covering an opening, add the left and right overlays to the opening width, then add the top and bottom overlays to the opening height. With a 1/2-inch overlay on all four edges, the finished door is 1 inch wider and 1 inch taller than the opening.
The chart below uses that specific overlay assumption. It is a dimensional reference—not a universal hinge requirement or confirmation that a door of that size will fit your cabinet hardware.
Single Overlay Cabinet Door Size Chart
“Single” means one door covers the opening; it does not identify a particular hinge type. Each example assumes a 0.500-inch overlay beyond each opening edge: left, right, top, and bottom.
| Opening width (in) | Opening height (in) | Overlay per edge (in) | Single door width (in) | Single door height (in) |
|---|---|---|---|---|
| 12 | 24 | 0.500 | 13.000 | 25.000 |
| 15 | 30 | 0.500 | 16.000 | 31.000 |
| 18 | 30 | 0.500 | 19.000 | 31.000 |
| 24 | 36 | 0.500 | 25.000 | 37.000 |
| 30 | 36 | 0.500 | 31.000 | 37.000 |
These are formula-derived finished-door dimensions, not rough blank sizes or hinge-capacity recommendations. Three decimal places show the arithmetic consistently; they do not specify a manufacturing tolerance. No rounding changes the results in this table.
How to Calculate Single Overlay Door Dimensions
Use the general formulas when the overlays differ between edges:
[
W_d = W_o + O_L + O_R
]
[
H_d = H_o + O_T + O_B
]
Where:
- (W_d) and (H_d) are the finished door width and height.
- (W_o) and (H_o) are the measured opening width and height.
- (O_L) and (O_R) are the left and right overlays.
- (O_T) and (O_B) are the top and bottom overlays.
Use the same unit for every value. Measure each overlay outward from its corresponding opening edge to the finished door edge.
If every edge has the same overlay (O), the formulas simplify to:
[
W_d = W_o + 2O
]
[
H_d = H_o + 2O
]
Example: An 18 × 30-Inch Opening
For an opening 18 inches wide and 30 inches high, with a 1/2-inch overlay at each edge:
- Door width: (18 + 0.5 + 0.5 = 19) inches.
- Door height: (30 + 0.5 + 0.5 = 31) inches.
The resulting finished door size is 19 × 31 inches.
For the equivalent metric calculation, use a 457.2 × 762 mm opening and a 12.7 mm overlay at every edge. The result is 482.6 × 787.4 mm. These are exact conversions of the inch example; substituting 13 mm for 12.7 mm changes the intended dimensions.
Measure the Opening, Not the Cabinet Exterior
Measure between the edges of the opening the door will cover. On a face-frame cabinet, use the opening inside the frame. On a frameless cabinet, use the opening between the relevant cabinet panels—not the cabinet’s overall outside dimensions.
Check the opening at multiple positions and compare diagonals before assigning one width and height. An out-of-square opening can produce uneven overlaps even when the door dimensions are calculated correctly.
Overlay and reveal are different measurements: overlay is the amount the door extends beyond an opening edge; reveal is the exposed margin or gap in the finished front layout. Do not subtract an additional generic gap from these formulas after choosing overlays that already account for the intended layout.
Check Hardware and Adjacent Fronts Before Cutting
Choose the intended overlay together with the hinge and cabinet construction. For example, Blum’s hinge quick reference relates overlay to hinge fixed distance, cup boring distance, and mounting-plate height. Its values apply to the corresponding hinge configurations, not to every cabinet hinge.
Before turning the calculated dimensions into a cutting or ordering specification:
- Confirm that the selected hinge supports the required hinge-side overlay and door thickness.
- Follow that hinge’s instructions for cup diameter, boring depth, edge distance, and mounting position.
- Check the closed-door margins and opening clearance beside neighboring doors, drawer fronts, fillers, and walls.
- Check the selected hardware’s door-size, weight, and hinge-count guidance, especially for wider or taller doors.
Do not use this single-door chart for two doors sharing one opening or for inset doors. Those arrangements require different sizing calculations. The dimensions here establish the intended finished rectangle; they do not determine hinge drilling locations or verify installation fit.