Canvas Depth Calculator

The canvas to cut for a stretched canvas, from the finished size, the wrap allowance and the edges being wrapped.

A gallery wrap is the reason a canvas ordered as 400 by 500 millimetres needs cloth of 500 by 600. The face is only part of the piece: the fabric has to run over the sides of the bar and fold onto the back, and a gallery wrap takes 50 to 75 millimetres on every wrapped edge where a standard wrap takes about 40. This calculator gives the fabric to cut, the wrap area and the fabric to order, on all four sides or on the top and bottom only.

At a glance

What you enter: Finished canvas length (long side), Finished canvas width (short side), Wrap type, Edges that wrap around the bar, Wrap allowance per wrapped edge, Fold allowance onto the back of the bar, Trimming margin on every edge, Canvas roll width, Price of canvas per square metre
What you get: Canvas length to cut, Canvas width to cut, Canvas to buy, Finished face area, Fabric that wraps, folds and trims, Share of the canvas that is not face, Fabric added per wrapped edge, Depth of bar the fabric will cover, Deepest bar this wrap suits, Length to order from the roll, Cost of the canvas fabric, Fabric cost per square metre of painting surface, Aspect ratio of the face
Formula shown: Yes, every step, right below your results.
Cost and privacy: Free, no account needed, and nothing you type is stored.

See worked examples ↓ Read the FAQ ↓ Share this calculator ↓

Finished canvas length (long side) mm

The face of the finished canvas, which is the outside dimension of the stretcher.

Finished canvas width (short side) mm

Wrap type

The value is the wrap allowance in millimetres per wrapped edge. A gallery wrap is hung without a frame, a standard wrap sits in one.

Edges that wrap around the bar

A canvas in a frame may only need two edges wrapped, because the rebate hides the others.

Wrap allowance per wrapped edge mm

The fabric that covers the side of the bar. Fifty to seventy five millimetres for a gallery wrap, about forty for a standard wrap.

Fold allowance onto the back of the bar mm

The fabric that folds onto the back and takes the staples. Fifteen to forty millimetres is the usual range.

Trimming margin on every edge mm

A little extra so an out of square cut can be corrected before stretching.

Canvas roll width mm

Common roll widths are 1500 mm and 2100 mm. Used to check the piece fits across the roll.

Price of canvas per square metre

Optional. Used for the fabric cost of the piece.

Reset

Results are estimates for general information only, always verify with a professional or official source before acting on them.

How to use the Canvas Depth Calculator

1 Enter Finished canvas length (long side) (mm), The face of the finished canvas, which is the outside dimension of the stretcher.
2 Enter Finished canvas width (short side) (mm)
3 Enter Wrap type, The value is the wrap allowance in millimetres per wrapped edge. A gallery wrap is hung without a frame, a standard wrap sits in one.
4 Enter Edges that wrap around the bar, A canvas in a frame may only need two edges wrapped, because the rebate hides the others.
5 Enter Wrap allowance per wrapped edge (mm), The fabric that covers the side of the bar. Fifty to seventy five millimetres for a gallery wrap, about forty for a standard wrap.
6 Enter Fold allowance onto the back of the bar (mm), The fabric that folds onto the back and takes the staples. Fifteen to forty millimetres is the usual range.
7 Enter Trimming margin on every edge (mm), A little extra so an out of square cut can be corrected before stretching.
8 Enter Canvas roll width (mm), Common roll widths are 1500 mm and 2100 mm. Used to check the piece fits across the roll.
9 Enter Price of canvas per square metre, Optional. Used for the fabric cost of the piece.
10 Press Calculate. You get Canvas length to cut, Canvas width to cut, Canvas to buy, Finished face area, Fabric that wraps, folds and trims, Share of the canvas that is not face, Fabric added per wrapped edge, Depth of bar the fabric will cover, Deepest bar this wrap suits, Length to order from the roll, Cost of the canvas fabric, Fabric cost per square metre of painting surface, Aspect ratio of the face, and every intermediate step stays visible under "How is this calculated?"
11 Change one number at a time to see what moves the result, that is usually the most useful thing a calculator can tell you.

Worked examples

Real numbers run through this calculator. Open any example to load it into the form above and change it.

A 400 by 500 mm canvas in a gallery wrap

A 50 millimetre wrap, a 25 millimetre fold and a 10 millimetre trimming margin on all four edges.

You enter

Finished canvas length (long side): 500 mm
Finished canvas width (short side): 400 mm
Wrap type: 2
Edges that wrap around the bar: 1
Wrap allowance per wrapped edge: 50 mm
Fold allowance onto the back of the bar: 25 mm
Trimming margin on every edge: 10 mm
Canvas roll width: 1,500 mm
Price of canvas per square metre: $14.00

You get

Canvas length to cut: 670.00 mm
Canvas width to cut: 570.00 mm
Canvas to buy: 0.38 sq m
Finished face area: 0.20 sq m
Fabric that wraps, folds and trims: 0.18 sq m
Share of the canvas that is not face: 47.6%
Fabric added per wrapped edge: 85.00 mm
Depth of bar the fabric will cover: 150.00 mm
Deepest bar this wrap suits: 40.00 mm
Length to order from the roll: 0.25 m
Cost of the canvas fabric: $5.35
Fabric cost per square metre of painting surface: $26.73
Aspect ratio of the face: 1.25

Each edge gains 85 millimetres, so the cloth is 670 by 570 millimetres, which is 0.38 square metres. About 47 percent of the fabric is wrap, fold and trim rather than face.

Open this example in the calculator →

The same face in a deep gallery wrap for a frame

A 75 millimetre wrap on the two long edges only, folded onto the back.

You enter

Finished canvas length (long side): 500 mm
Finished canvas width (short side): 400 mm
Wrap type: 1
Edges that wrap around the bar: 2
Wrap allowance per wrapped edge: 75 mm
Fold allowance onto the back of the bar: 30 mm
Trimming margin on every edge: 10 mm
Canvas roll width: 1,500 mm
Price of canvas per square metre: $14.00

You get

Canvas length to cut: 730.00 mm
Canvas width to cut: 400.00 mm
Canvas to buy: 0.29 sq m
Finished face area: 0.20 sq m
Fabric that wraps, folds and trims: 0.09 sq m
Share of the canvas that is not face: 31.5%
Fabric added per wrapped edge: 115.00 mm
Depth of bar the fabric will cover: 210.00 mm
Deepest bar this wrap suits: 65.00 mm
Length to order from the roll: 0.19 m
Cost of the canvas fabric: $4.09
Fabric cost per square metre of painting surface: $20.44
Aspect ratio of the face: 1.25

The long edges gain 115 millimetres each and the short edges gain nothing, so the cloth is 730 by 400 millimetres. Wrapping two edges only saves fabric but leaves the short edges to the frame rebate.

Open this example in the calculator →

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Frequently asked questions

How much extra canvas do I need for a gallery wrap?

Fifty to seventy five millimetres on each wrapped edge for the visible side of the bar, plus 15 to 40 millimetres for the fold that staples to the back, plus a trimming margin. A 400 by 500 millimetre face with a 50 millimetre wrap, a 25 millimetre fold and a 10 millimetre margin needs cloth of 500 by 600 millimetres, which is half as much fabric again as the face. A deeper bar needs a longer wrap, so measure the stretcher you intend to use.

What is the difference between a gallery wrap and a standard wrap?

A gallery wrap covers the sides of the bar with painted canvas so the piece can hang without a frame, and it therefore needs 50 to 75 millimetres per wrapped edge plus enough fold to hold a staple. A standard wrap takes about 40 millimetres and is designed to sit inside a frame, whose rebate hides the edges. A gallery wrap uses more fabric and needs a deeper bar, but it saves the cost of a frame and it shows the edge of the composition, which has to be planned for.

Do all four edges of a canvas need to wrap?

Only if the sides will be visible. A canvas going into a frame with a deep rebate can have just two edges wrapped, which saves fabric on the other dimension, but the rebate has to be deep enough to cover the unwrapped edges and their staples. Wrapping all four edges is the safer choice, because a frame with a shallow rebate exposes the edge and there is nothing to be done about it once the canvas is cut.

How do I work out the canvas area for a roll order?

Cut length times cut width gives the piece, and that is the area the supplier charges for unless they sell by the running metre. A 500 by 600 millimetre piece is 0.3 square metres. On a roll, check that the cut width fits across the roll width: a piece wider than the roll has to be joined, and the join will show on the face of the painting. Order in one length, because a join is a visible seam and a weak point on a stretched canvas.

Should I add a trimming margin?

Yes, a small one. Cutting canvas to the exact calculated size leaves no room to correct a cut that is a few millimetres out of square, and a canvas that is not square stretches into a painting that is not square. Ten millimetres on every edge is enough to correct a small error and to give the pliers something to grip on the first pull. It is a small increase in fabric and it can save the piece.