Picture Frame & Mount Sizes Guide
Choosing the right frame and mount transforms how artwork is presented. This reference covers standard UK frame sizes, recommended mount border widths, how to calculate mount apertures, and a comparison of glass types available for framing.
Standard UK Frame Sizes
These are the most commonly available ready-made frame sizes in the UK. Sizes refer to the image area (the opening), not the outer frame dimensions.
| Size (inches) | Size (cm) | Aspect ratio | Typical use |
|---|---|---|---|
| 4″ × 6″ | 10 × 15 cm | 2:3 | Standard photo prints |
| 5″ × 7″ | 13 × 18 cm | 5:7 | Small photos, desk frames |
| 6″ × 8″ | 15 × 20 cm | 3:4 | Small prints, certificates |
| 8″ × 10″ | 20 × 25 cm | 4:5 | Portraits, small artwork |
| 10″ × 12″ | 25 × 30 cm | 5:6 | Medium prints, watercolours |
| 12″ × 16″ | 30 × 40 cm | 3:4 | Popular medium frame size |
| 14″ × 18″ | 35 × 45 cm | 7:9 | Medium–large artwork |
| 16″ × 20″ | 40 × 50 cm | 4:5 | Gallery-standard medium size |
| 20″ × 24″ | 50 × 60 cm | 5:6 | Large prints, exhibition work |
| 20″ × 30″ | 50 × 76 cm | 2:3 | Large photographs, panoramic |
| 24″ × 36″ | 60 × 91 cm | 2:3 | Posters, large statement pieces |
Recommended Mount Border Widths
A mount (mat in US terminology) provides visual breathing room around the artwork and prevents it touching the glass. The bottom border is traditionally slightly wider than the top and sides to counteract an optical illusion that makes equal borders look bottom-heavy.
| Frame size | Top & sides | Bottom | Notes |
|---|---|---|---|
| Up to 8″ × 10″ | 38–50 mm (1.5–2″) | 50–63 mm (2–2.5″) | Minimum mount for small frames |
| 10″ × 12″ to 14″ × 18″ | 50–63 mm (2–2.5″) | 63–75 mm (2.5–3″) | Standard mount for medium frames |
| 16″ × 20″ to 20″ × 24″ | 63–75 mm (2.5–3″) | 75–100 mm (3–4″) | Generous mount for gallery presentation |
| Over 20″ × 24″ | 75–100 mm (3–4″) | 100–125 mm (4–5″) | Large work benefits from wider mounts |
The mount aperture is typically cut 3–5 mm smaller than the artwork on each side, so the mount overlaps the edge of the image. This gives a clean edge and holds the work in place.
Glass Types for Framing
The choice of glazing affects the appearance, protection and cost of your frame. Here is a comparison of the most common options available in the UK.
| Type | UV protection | Anti-reflective | Weight | Best for |
|---|---|---|---|---|
| Standard float glass | ~45% | No | Heavy | Budget framing, posters |
| Non-reflective glass | ~45% | Yes (diffused) | Heavy | Reducing glare; slightly hazy appearance |
| UV-filtering glass | ~99% | No | Heavy | Protecting valuable artwork from fading |
| Museum glass | ~99% | Yes (optical coating) | Heavy | Premium framing, galleries, maximum clarity |
| Standard acrylic (Perspex) | ~50% | No | Light | Large frames, shipping, safety |
| UV acrylic | ~99% | No | Light | Large frames needing UV protection |
Framing Calculators
Use our free tools to calculate mount sizes, frame dimensions and costs:
- Mount Size Calculator — work out mount border widths and aperture dimensions
- Frame Size Calculator — find the right frame for your artwork and mount
Frame sizes are nominal — actual rebate (rabbet) sizes may be 1–2 mm larger. Always measure your artwork before ordering a frame. Mount board thickness is typically 1.4 mm (standard) or 2.0 mm (conservation grade).