Disclaimer

The results are estimates

Each calculator applies a written-down formula to the numbers you enter. By default it rounds to the nearest 1/16 inch or millimeter, because that is what you can cut to. Switch on Decimals if you need the exact figure. A mistyped measurement, or a fraction read off the wrong mark on a ruler, gives a confident but wrong answer.

Conventions are not rules

The ¼″ overlap per side, the ¼″ double-mat reveal and bottom-weighting are where most framers start, not measurements anyone has standardized. Your frame shop, your artwork or your own taste may call for something different, and that is fine.

Measure the real frame and materials

Frames sold as the same size are not always the same inside. Rabbet sizes vary between makers, pre-cut mats differ by a sixteenth or two, and glass, acrylic and backing come in different thicknesses. Measure the frame you actually have, and treat a calculator result as a figure to confirm against the frame in your hands.

Cutting safely is on you

Mat cutters, utility blades and glass all cut people as well as board. Follow the instructions that came with your tools and materials. FramingMath tells you where to cut, not how to cut safely.

Not professional or conservation advice

The guides describe common practice for home and hobby framing. For valuable, old or irreplaceable work, such as original art, family documents or heirloom textiles, talk to a professional picture framer or a conservator before you mount, mat or glaze it.

Materials and liability

FramingMath is not responsible for miscut mats, wasted board or glass, frames bought in the wrong size, or any other loss from using the site. The full wording is in our terms of use.

Advertising and other sites

Any ads on FramingMath come from third-party networks such as Google, and an ad is not a recommendation from us. The few links that lead off the site go to pages we don't control. Our privacy policy explains the data side.

Found a mistake?

If a number looks wrong, stop before you cut and email support@framingmath.com with the calculator's share link. The contact page lists what to include in a report.