Picture Frame Size Calculator
Enter your artwork size and framing specs to calculate mat opening, outer frame dimensions, and total moulding needed.
Why use a frame calculator?
A frame calculator helps artists, photographers, DIYers, and professional framers avoid the two most common framing problems: ordering material that is too short and cutting mats that do not align with the artwork. With a few measurements, you can quickly determine finished outer dimensions, mat opening size, and total moulding length.
Whether you are framing one family photo or producing a full gallery wall, a structured calculation process saves money, time, and frustration.
How this frame calculator works
1) Start with the art size
Enter the visible artwork width and height. These are the true dimensions of the print, photo, certificate, or canvas panel you want to frame.
2) Add your mat border
If you are using a mat board, enter the border width for each side. The calculator adds this to both width and height to determine the mat’s outer size and the glass/backing size.
3) Set frame moulding width
The moulding width contributes directly to the final outside dimensions. Wider mouldings create a larger finished frame and require more material.
4) Include rabbet overlap and waste
Rabbet overlap is how much of the artwork edge is covered by the frame lip. Waste allowance accounts for trim loss, knot avoidance, and miter mistakes.
What the results mean
- Mat opening: the window cut in the mat board (art size minus overlap on each side).
- Glass/backing size: typically matches the mat’s outer dimensions.
- Finished frame outer size: final width and height from outside edge to outside edge.
- Moulding required: total linear length needed for all frames, including waste.
Quick best practices for accurate framing
Measure twice, cut once
Use a rigid ruler or metal tape measure. Soft tape measures can drift on smaller dimensions.
Use realistic waste percentages
For beginners, 10-15% waste is usually safer. For experienced framers with repeat cuts, 5-10% may be enough.
Keep unit consistency
Do not mix centimeters and inches in one project. Pick one unit for every input and every cut list.
Example scenario
Suppose you frame a 16 × 20 print with a 2-inch mat border and 1.5-inch moulding. Add a 0.25-inch overlap and 10% waste. The calculator instantly gives you:
- Correct mat opening dimensions
- Glass/backing size for ordering
- Finished outer frame size for wall planning
- Total moulding required for purchase
This is especially useful when batching multiple frames in a studio, school, office, or exhibition setup.
Common mistakes a frame calculator prevents
- Buying moulding based only on artwork perimeter
- Forgetting to account for frame width on both sides
- Cutting a mat opening the same size as the art (no hold-down overlap)
- Running short on material due to no waste buffer
Final thoughts
A dependable frame size calculator is one of the simplest upgrades you can make to your framing workflow. It produces cleaner planning, faster purchasing, and more predictable finished results. Use this tool before every project and keep your framing process consistent from first measurement to final hanging.