How to Measure for Oversized Frames: A Practical Guide

Getting a large picture frame made for your favourite artwork starts with accurate measurements. One small slip and the finished frame might not fit the piece properly. We have been building bespoke frames at Harten since 1974, much of it oversized work, and the measuring method below is the one we give every client.

Why the measurements matter

Oversized frames are not off-the-shelf items. Everything is cut and assembled for your piece: the frame itself, the glazing, mounts and backing. The dimensions you give us set the internal space, called the rebate, where the artwork sits. If it is out by even a little, the art can sit loose or too tight. Production starts promptly on custom work, so time spent measuring carefully at the start saves real trouble later.

What you will need

A sturdy metal tape measure, ideally the retractable kind, because it stays rigid and reads accurately. A clean, flat surface big enough to lay the artwork out without curling or bending. Paper and a pen for the numbers, and a second pair of hands if the piece is heavy or awkward. Avoid fabric tapes: they stretch and throw the numbers off.

How to measure prints and flat artwork

Lay the artwork face up and smooth it out completely, with no bumps or curled edges. Measure the full width from left to right and the height from top to bottom, right to the edges. Take the width at the top, middle and bottom, and the height at both sides, in case the sheet is not perfectly square. Use the largest numbers if they differ.

If the print has a white border you want fully visible, include it. If a mount will overlap the edges slightly, which is common and hides any imperfections, measure just the image area you want showing. Always work in millimetres, width first, then height: 1200mm x 900mm, for example. Then check everything once more. It takes a minute and catches most errors.

How to measure a stretched canvas

For stretched canvases, measure the front face edge to edge at several points and take the widest and tallest figures. Canvases can warp slightly over time, so checking multiple spots avoids surprises. Measure the depth of the stretcher bars along the side as well, so the rebate is cut deep enough. If the canvas is irregular or unusually thick, a floater frame is worth considering: it surrounds the canvas with a small gap and shows the edges without overlapping the front.

How frame dimensions work

The internal rebate is made to your exact artwork measurements so the piece slots in snugly. From the front, the frame's inner lip overlaps the edges by a few millimetres to hold everything securely. That overlap is standard and keeps the piece safe without slipping. Give us the true sizes and the workshop handles the rest; there is no need to add any allowance yourself.

Adding a mount

A mount, the card border around the artwork, gives the piece breathing space. For oversized work a width of 50mm to 100mm or more on each side usually balances the scale. The overall frame size then becomes the artwork dimensions plus twice the mount width in each direction. We can advise on proportions that suit the piece.

When the piece passes two metres

Two metres on the long edge is the point where an oversized frame becomes a specialist build: two-person handling, polycarbonate glazing in place of acrylic, and delivery by our own van rather than a courier. If your piece is anywhere near that size, measure the access route as well as the artwork: door widths, stair turns and ceiling heights on the way to the wall. Our guides to extra large picture frame costs and how extra large frames are delivered cover what changes at this scale and why.

If measuring feels tricky

Large or valuable pieces can be nerve-wracking to handle. Many clients send the artwork to us instead, and we measure it professionally in the workshop before quoting and framing. For fragile or heavy pieces it is often the safest route, and we are happy to talk a project through early on. If you are unsure, just get in touch.

A few pointers from experience

Measure in a well-lit spot and keep the tape straight and level. Give the true sizes, with no extra allowance added. Do not rely on old labels or generic size charts, because artwork shifts over time. Whether you are an artist preparing work for exhibition or framing a personal collection, careful numbers at the start mean a frame that fits perfectly and protects the piece for years.