How much should the mat overlap the print?

The mat opening should be slightly smaller than the print — typically 3-5mm overlap on each side. This overlap holds the print in place behind the mat and ensures no white paper edge shows through. Too much overlap hides important image content.

Should the bottom border be wider?

Traditionally, yes. A slightly wider bottom border (1-2cm extra) compensates for an optical illusion where centred images appear to sag downward. This is called bottom weighting. For a modern, clean look, equal borders all around also works well.

What is a standard mat border width?

For gallery presentation, 5-8cm borders are standard. Smaller prints (A4 and under) suit 5cm borders. Larger prints (A3+) suit 6-8cm. Very large exhibition prints may use 10cm+ borders. The border should frame the image without overwhelming it.

What colour mat should I use?

White or off-white mats are the safest choice and suit most images. Cream/ivory works well with warm-toned or vintage images. Black mats create a modern, dramatic look. Coloured mats should complement the image without competing with it. Always use acid-free mat board for archival framing.

PhotoCalcs

Mat Board Calculator — Opening & Border Sizes

Calculate mat board opening size and border widths for professional print presentation.

Print Width

Width measurement

Print Height

Height measurement

Border Width

Side and top border

Extra Bottom Border

Bottom weighting

Mat Overlap

Overlap on each side

How We Calculate This

Mat Opening

Opening = print size - (2 x overlap)

Outer Mat Size

Width = opening + (2 x side border)

Height = opening + top border + bottom border

Bottom border = standard border + extra bottom weight.

Frequently Asked Questions

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Last updated: February 2026

All calculations are estimates based on standard optical and photographic formulas. Results may vary with specific equipment.