Canvas to cut for stretching.

Worked example

Stretcher bars 16 x 20 in, 0.75 in deep, with a 2 in grip allowance. Added on each side: 0.75 + 2 = 2.75 in, so 5.5 in per direction. Cut size: 16 + 5.5 = 21.5 in by 20 + 5.5 = 25.5 in. Three pieces from a 60 in wide roll: two 25.5 in sides fit across (51 in), so the pieces go two to a row, two rows, and the length is 2 x 21.5 = 43 in, or 1.19 yd. At $12 per yard that is $14.33.

How it works

Canvas has to cover the front of the bars, wrap round the depth of the bars, and leave spare on the back to grip with canvas pliers and staple. So each direction needs the bar size plus two times the bar depth plus two times the grip allowance. The grip allowance is a working rule of thumb from experience; measure what your own pliers need.

For several pieces, the calculator tries laying them across the roll both ways and keeps the shorter roll length. It does not nest pieces more cleverly than whole rows, so treat the length as the amount to buy, not the minimum possible.

Sources and basis (opened 2026-10-08): 1 in = 2.54 cm and 36 in = 1 yard from Inch (Wikipedia); the grip allowance is a common rule of thumb, not a published standard.

FAQ

How much bigger than the stretcher bars should I cut canvas?

Bar depth plus a grip allowance on every side. For 0.75 in deep bars and a 2 in grip that is 2.75 in per side, so a 16 x 20 in frame needs 21.5 x 25.5 in.

Does bar depth matter?

Yes. Deeper gallery bars need more canvas to wrap round them. Measure the depth of your bars, not the catalogue name.

How much roll do I need for several canvases?

43 in (1.19 yd) of 60 in wide canvas for three 16 x 20 in frames in the example. The calculator checks both orientations.

Should I prime before or after stretching?

Either works; people differ. If you prime the roll first, cut and stretch afterwards. The cut size is the same.

Is the grip allowance fixed?

No. 2 in is a rule of thumb; use less if you staple the sides directly and more if you like a lot to pull on.