How Much Fabric for Cushions and Pillows?
A box cushion is a surprisingly small amount of fabric arranged in a specific way. The interesting part is what happens when you make more than one, because the second is often close to free.
Measure the Insert, Not the Old Cover
An old cover has stretched, and a foam pad that has been sat on for six years is not the size it started at. Measure the insert you are actually covering, and measure it without pressing the tape into the foam. A cover cut to a squashed measurement will sag.
You need three numbers: width from side to side, length from front to back, and thickness at the boxing. Then decide the shape, because a box cushion, a round seat pad and a bolster are worked out completely differently. If you are replacing a cover you like, unpicking the old one gives you a better cut list than any calculation.
One Cushion, Piece by Piece
Take an 18 by 18 by 3 inch box cushion on 54 inch fabric with a zipper. The cushion calculator builds it as one long wrap that goes over the top, down the front, under the bottom and up the zipped back, plus two small strips for the ends.
- Main wrap: 19" wide × 46.25" long (19 top + 4 front + 19 bottom + 4.25 zip side)
- Side strips: two, each 4" × 19"
- Wrap row: 46.25" of length
- Strip row: both strips sit side by side, so 19" of length
- Total: 65.25 ÷ 36 = 1.8, so 2 yards
Notice the strips. They are only 4 inches wide, so thirteen of them would fit across a 54 inch bolt. Putting two of them in one row instead of end to end is the difference between 2 yards and 2.5. That kind of packing is where cushion yardage is won or lost.
Order the Whole Set at Once
Here is the part worth knowing before you buy. The main wrap is 19 inches wide, and two of those fit across 54 inch fabric with room to spare. So a second identical cushion slots into the same row as the first.
Two of these cushions come to the same 2 yards as one. Ordered separately on two different days, they cost 4. The fabric did not change and neither did the cushions. Only the order did.
This is why it pays to plan a whole set in one go: a window seat, a set of dining pads, a bench and its matching back. Put the full quantity into the calculator rather than working out one cover and multiplying, because multiplying is exactly the mistake that makes you overbuy.
Piping Gives You a Cord Length, Not Fabric
Turn piping on for that same cushion and the calculator reports 4 yards. That is 4 yards of cord, the string that goes inside. It is not fabric, and it has not been added to your yardage.
If you are covering that cord yourself you need bias strips, and bias strips are cut diagonally across the cloth, which uses more than their length suggests. Work them out separately and add them on. Plenty of people use a contrast fabric or buy ready made piping instead, which sidesteps the whole problem and is often the cheaper answer for a small job.
Round, Bolster and Bench Are Not the Same Sum
- Round pads are cut as squares that contain the circle, so a 20 inch round seat needs a 21 inch square and the corners are waste. Round is always less efficient than square.
- Bolsters are a rectangle wrapped round a tube plus two end circles. The rectangle length is the circumference, so a small change in diameter moves it by more than you expect.
- Bench cushions use the same wrap as a box cushion until the bench is wider than the fabric. Past that point the wrap is joined from sections, and the seams have to be planned rather than landing wherever.
For outdoor seating, the fabric choice matters as much as the number. The outdoor fabric guide covers what survives a few summers and which thread outlasts the cloth.