Picture Frame Measurements Calculator
Direct Answer: Calculating picture frame measurements is based on the inside glass/rabbet size, not the outer moulding. If adding a matboard: Frame Size = Photo Dimensions + (2 × Mat Border Width). To keep the artwork from falling through, cut the mat opening 1/4" smaller than the photo (1/8" overlap on all four edges).
Picture Frame & Mat Size Calculator
Input your photo and matboard dimensions for instant frame glass calculations:
Enter 0 if framing without a matboard.
Standard Picture Frame Sizes & Common Mat Pairings
Buying standard ready-made frames is typically significantly more economical than custom framing. Use this guide to pair standard photo prints with standard off-the-shelf frame sizes.
| Frame Glass Size | Best Artwork Size (With Mat) | Mat Border Width | Ideal For |
|---|---|---|---|
| 5" × 7" | 3.5" × 5" (or no mat 5×7) | 0.75" to 1" | Desktop portraits & school photos |
| 8" × 10" | 5" × 7" print | 1.5" border | Most popular family photo size |
| 11" × 14" | 8" × 10" print | 1.5" to 2" border | Certificates, diplomas & wedding photos |
| 16" × 20" | 11" × 14" print | 2.5" to 3" border | Gallery wall centerpieces |
| 24" × 36" | 18" × 24" (or no mat 24×36) | 3" border | Movie posters & large art prints |
Common Picture Framing Mistakes
Cutting the Mat Opening to Exact Photo Size
If your print is 8×10 and you cut the mat window exactly 8×10, the photo will fall straight through the hole! You must cut the opening 1/4" smaller (7-3/4" × 9-3/4") so the mat overlaps the photo edges by 1/8".
Measuring Outside Moulding Instead of Glass
Picture frames are sold by their interior glass dimensions (the "rabbet"). A wide 3-inch ornate frame labeled "8×10" has an outer footprint of 14×16, but its interior glass is still exactly 8×10.
Ignoring Rabbet Depth with Stretched Canvases
Standard photo frames typically have an internal groove depth of roughly 3/8" (about 9 mm), designed primarily for paper prints, mats, and backing. Stretched canvas bars are commonly 3/4" to 1.5" thick and usually require deep-rabbet canvas frames or offset clips.
Zero Allowance for Seasonal Expansion
Paper matboard and wooden frames absorb atmospheric humidity and expand. Cutting mats with zero tolerance can cause the mat to buckle against the glass. Framers commonly allow roughly 1/16" to 1/8" total clearance under the interior rabbet opening for natural expansion.
Frequently Asked Questions
How do I measure a picture frame size?
Frame size is the size of the artwork or photo the frame holds, given as width by height in inches. Measure the opening (the visible area behind the glass) rather than the outside edge of the frame.
What does 11x14 mean for a picture frame?
It means the frame holds an 11 inch wide by 14 inch tall print or mat. With a mat, an 11x14 frame commonly displays an 8x10 photo.
What are standard picture frame sizes?
Common US sizes are 4x6, 5x7, 8x10, 11x14, 16x20, 18x24 and 24x36 inches. See the reference table above.
How big should the mat opening be?
The mat opening is usually about 1/4 inch smaller than the photo in each direction, so the mat overlaps the photo by about 1/8 inch per side. The calculator above shows the photo, mat and final glass size.
How do I figure out my frame size with a mat?
Add the mat border to both sides of the visible photo area. For example, an 8x10 photo with a 1.5 inch mat border on every side needs an 11x13 outer mat size, so choose a frame that matches that size.
Is 20x26 a standard frame size?
It is not among the most common ready-made sizes, so it is often custom. 20x24 and 20x30 are easier to find.