What is a weighted bottom border?

A weighted bottom border is slightly larger than the top and sides (typically 15% larger). This compensates for an optical illusion that makes equally-sized borders appear to have a smaller bottom. The weighted bottom looks visually balanced.

How much overlap should the mount have?

Standard overlap is 5 mm on each side — the mount covers 5 mm of the artwork edge. This hides rough edges, tape marks and uneven borders. For prints with printed borders, reduce overlap to 2-3 mm.

What border width should I use?

Standard mount borders are 50-80 mm. For small works (under A4), use 50-65 mm. For medium works (A4-A3), use 65-80 mm. For large works, 80-100 mm. The border should be proportional to the artwork — not too narrow or too wide.

What is the bevel cut?

The mount opening is cut at a 45-degree angle (bevel). The bevel reveals the white core of the mount board, creating a subtle frame around the artwork. A good bevel cut is the mark of professional framing.

Should I use equal or weighted borders?

Weighted bottom borders are traditional and recommended for most framing situations. Equal borders can look bottom-heavy due to the optical illusion. Only use equal borders for very modern, minimalist presentations.

ArtCalcs

Mount Opening Calculator — Weighted Bottom Border

Calculate the mount opening dimensions with weighted bottom border.

Artwork Width

Artwork Height

Border Width

Top and side borders

Overlap

Mount covers artwork edge

Weighted Bottom

How We Calculate This

How Mount Opening Calculation Works

Opening = Artwork size - (Overlap x 2)

Mount = Opening + Borders

The mount opening is smaller than the artwork by the overlap amount on each side. The weighted bottom border is 15% larger than the top border. The overall mount size equals the opening plus borders on all four sides.

Frequently Asked Questions

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Last updated: February 2026

All calculations are estimates. Always verify quantities before purchasing materials.