Glass Size Calculator — Glazing for Picture Frames

Glass is sharper optically and more scratch-resistant. Acrylic (Perspex) is lighter and shatter-resistant, making it better for large frames, shipping and public spaces. Museum glass offers the best of both but costs significantly more.

Allow 2 mm total clearance (1 mm each side) for glass to fit in the rebate without being too tight. Glass that is cut to the exact rebate size may crack from frame expansion.

Oil and acrylic paintings on canvas are usually displayed without glass. Works on paper (prints, watercolours, photographs, pastels) should always be glazed for protection. Charcoal and pastel work especially needs glazing with a spacer to prevent contact.