A tufted panel is bigger before it is smaller
Pull a button down into foam and the cover has to travel with it. It goes down as far as the button sits and comes back out on the other side, and that whole journey is cloth that used to be lying flat across the face of the panel. It is gone from the width and it is gone from the height, and it is gone at every single button.
The arithmetic is not complicated. Two times the depth per button, times however many buttons you cross going that way. On the panel in the form — 48 by 30 in, buttons at 8 in across and 6 in down, half an inch of draw-up — that is six dips across the width and five down the height, so 6 in goes into the width and 5 in into the height. Add the edge allowance and the cover gets cut at 55 by 36 in for a panel that finishes at 48 by 30.
The number that catches people
Fifty-five inches will not go across 54 in goods. Forty-nine inches would have, comfortably. The tufting is the entire difference, and it is the kind of thing that gets discovered when the cloth is already on the table and already paid for.
There are only three ways out and all of them are decisions rather than fixes: turn the panel so the 36 in dimension runs across the goods, which is fine on a plain cloth and impossible on a velvet or a one-way print; put a seam in, which on a tufted panel has to be hidden in a tuft line; or buy wider goods. The page prints whether the panel would have fitted untufted precisely so this shows up while it is still a purchasing question.
Where the depth figure comes from
Not from here. The draw-up depth depends on the foam far more than on anything else, because a soft foam lets the button sink much further at the same twine tension than a firm one does. Two panels with identical grids and identical cloth can want visibly different allowances if the foam under them is different.
The way to get a real number is a mock-up, and it takes twenty minutes. Cut a square of the actual foam, put a square of the actual cloth over it, tuft it at the actual spacing, and measure how much cloth got eaten. Divide that by the number of dips and you have your own figure. The take-up factor on the form exists so you can carry that correction across without recalculating everything else.
Diamond against square
Same spacing, different counts. A square grid puts a button at every intersection: six across on five rows is thirty. A diamond offsets alternate rows by half a space, and those offset rows sit one button short — three rows of six and two rows of five, which is twenty-eight.
Two buttons is not much, but it scales, and it changes the twine, the covered buttons and the width allowance with it. What it does not change is the draw-up down the height, because both layouts have the same number of rows. That asymmetry is worth knowing when you are deciding which way a panel is cut.
Twine and covered buttons
Twine goes through the foam and back, plus a tail at the back to tie off. Through 3 in of foam with a 3 in tail that is 12 in a button, so twenty-eight buttons take 28 ft. It is not much material and it is entirely predictable, which makes it the easiest thing on the whole job to run short of at ten at night.
Covered buttons need a fabric circle roughly twice the finished diameter for a flat button, more for a deep one, and the die chart that came with the machine is the authority on that rather than any general rule. At 1.125 in buttons with a two-times circle that is 2.25 in a circle, twenty-three across 53 in of usable goods, two rows for twenty-eight buttons — four and a half inches of cloth. Cut them from the offcut, and cut them from the same part of the bolt as the panel if there is any chance the dye lot moves.
What this page will not tell you
Whether a grid is right, what twine or shank will hold, or what foam belongs under a tufted seat. Button size numbers are not consistent between makers, so the diameter on the form is one you measure. And deep tufting keeps a cover under tension at every button for as long as the piece exists, which is a construction question for whoever is specifying the work.
Questions people ask
How much bigger do you cut fabric for tufting?
Twice the draw-up depth for every button you cross in that direction. On the panel in the form — six buttons across, five rows down, half an inch of draw-up — that is 6 in added across the width and 5 in down the height, so a 48 by 30 in face gets cut at 55 by 36 in with the edge allowance. Cut it at the finished size and it finishes short at the edges with nothing to staple.
How do I work out the draw-up depth?
Measure it, because it depends on your foam. Tuft one square of the actual foam with the actual cloth at the actual spacing, measure how much cloth disappeared, and divide by the number of dips. Soft foam lets a button sink much further at the same tension than firm foam does, so a figure borrowed from another job is a guess.
How many buttons in a diamond tufting pattern?
Fewer than a square grid at the same spacing, because every offset row is one button short. Six across on five rows is thirty buttons square and twenty-eight diamond — three rows of six and two rows of five. It changes the twine and the covered buttons with it, but not the draw-up in the height, since the row count is the same either way.
How much twine does tufting take?
Through the foam and back, plus a tail to tie off. Through 3 in of foam with a 3 in tail that is 12 in a button, so twenty-eight buttons take 28 ft. The tail length is your own practice and the field is there to hold your figure rather than one this page supplies.
How big a fabric circle does a covered button need?
Roughly twice the finished diameter for a flat button and more for a deep one, but the die chart that came with your button machine is the real authority and it is specific to the dies you own. At 1.125 in buttons with a two-times circle that is a 2.25 in circle, and twenty-eight of them take about four and a half inches off a 54 in goods.