What Size Frame for an A-Sized Print? A Sizing Guide for A6 to A0

A-sizes are the standard UK paper sizes, so most prints, posters and photographic enlargements arrive at a known A-series dimension. Framing one means matching that print to a frame size, almost always with a mount around it. There are two ways to do that: take the simple ready-made route, or set the frame size yourself with a chosen mount margin.

This guide covers the dimensions of every A-size from A6 to A0, the frame size each one needs, the mount margins that look right at each scale, and three worked examples. The figures are guidance for getting a balanced result, not a fixed standard, so treat the margins as a starting point you can adjust to taste.

A-series print sizes

Each A-size is exactly half the one above it, which is why the proportions stay consistent as the sizes scale up. The table below gives the dimensions in both millimetres and inches.

What size frame for each A-size

The simplest approach is to mount the print into the next A-size up. An A4 print sits in a mount with an A4 aperture and an A3 outer, which then fits an A3 frame, and the same logic carries up the range. This is how most ready-made frames and pre-cut mount packs are built, so it is the quickest route for standard work. For the matching frame-size reference across A-series and imperial dimensions, see our standard picture frame sizes guide.

If you want a specific mount margin rather than the standard reveal, the frame is sized to the artwork plus twice your chosen margin. The table below gives both: the ready-made frame size, and a bespoke outer size using a typical margin for each scale. The margins widen as the print grows, because a small border that looks generous on an A5 print looks tight on an A1.

Mount margins and aperture

The aperture is the window cut into the mount that the print shows through. It is cut a few millimetres inside the print on each side, typically 3 to 5mm, so the mount holds the edges without hiding any of the image. The margin is the visible border of mount around that window, and it is the part that changes how the framed piece feels. As a rule of thumb, 30 to 50mm suits photographs and 50 to 75mm suits fine art, with the bottom margin often set slightly wider than the top and sides so the print does not look as though it is slipping down inside the frame. For aperture dimensions and window styles in full, see our standard mount sizes reference.

Worked examples

Framing an A4 photograph. An A4 print at 210 × 297mm is the most common framing job in the UK. The quick route is an A3 frame with an A4 aperture mount, which gives roughly 45mm of border. For a slightly more generous look, a bespoke 60mm margin gives an outer frame of about 330 × 417mm. Standard glazing is fine for most photographs, though a print hung near a window benefits from UV-filtering glass.

Framing an A2 archival print. An A2 limited-edition giclée at 420 × 594mm reads best with a wider margin, around 75mm, for a bespoke outer of roughly 570 × 744mm. Because archival pigment prints are made to last, a conservation mount and UV-filtering glazing are the sensible specification here. Conservation and museum-grade are tiered rather than the same thing, so the right level depends on the value of the edition.

Framing an A0 botanical. An A0 print at 841 × 1189mm is large enough that it sits at the bottom of oversized territory. With a 100mm margin the outer frame is around 1041 × 1389mm, and at that scale the frame itself needs a deeper, sturdier profile to stay rigid. Work at this size or larger is handled as oversized framing rather than standard framing.

When to frame without a mount

A mount is not always the right call. Gallery-wrap canvas is framed without glass or a mount, usually in a float or tray frame so the edges sit proud. Contemporary prints designed to bleed to the paper edge lose their effect behind a mount, and some prints carry their own printed border that is meant to be seen. In these cases the frame is sized to the print itself plus the frame rebate, with no mount margin added.

Custom framing for any A-size

The sizes above cover standard A-series work, but a frame can be built to any dimension once you move off the ready-made grid. We cut mounts to the millimetre on a Gunnar precision mount cutter and build the frame to match, so the margin, aperture and profile are all chosen for the specific print. Bespoke custom framing starts from around £200 for a standard piece, with the mount and frame covered together by our 5-year guarantee. Send the print dimensions and the look you are after, and we will recommend the frame and mount size for the piece.