# Cushion fabric calculator

A cushion cover is a front, a back in one piece or two, and often a run of piping — so the fabric it takes depends on how those rectangles pack across your roll rather than on their total area. An envelope back adds two pieces of about 60% of the cover height each, a zip adds one the size of the front, and piping is cut in strips across the width. The calculator below builds that piece list from your cover size, packs it onto the roll and prints the cutting plan, in metric or imperial.

Source: https://fabricmeasure.com/calculators/cushion-fabric-calculator/
Last updated: 2026-08-20 (method v1)
Published by FabricMeasure.

---

## The formula

A cover is a piece list, and the piece list is packed onto the roll in rows.

```
cover        = cushionSize + 2 x border
front        = cover x cover                          x quantity
envelopeBack = cover wide x (0.6 x coverHeight + 5 cm hem)   x quantity x 2
zippedBack   = cover x cover                          x quantity
piping       = quantity x (2 x (coverW + coverH) + 10 cm to join)
strips       = ceil(piping x biasFactor / usableWidth)   each 4 cm of length
```

Bias strips carry a factor of sqrt(2) - about 41% more cloth - because a diagonal strip
covers less of the roll for the same run of piping. Straight grain has no factor.

Those pieces then go through the shared cutting layout: seam allowances on every edge,
widest piece first, each piece into the first row with room for it, and a row costs the
length of the longest piece in it. Rounding is upward at every step.

## Sizing the cover

Cut the cover 2-3 cm SMALLER in each direction than the insert. A cover the same size as its
pad hangs slack at the corners; an undersized one is filled out and holds a square shape.

## Worked example

4 covers finishing at 45 x 45 cm, envelope backs, no piping, 140 cm plain fabric, 1.5 cm seams.

| Step | Working | Result |
| --- | --- | --- |
| Envelope back pieces | 2 per cushion, each 60% of 45 cm + 5 cm hem | 45 cm × 32 cm |
| Pieces to cut | 4 × front, 8 × envelope back, each grown by 3 cm for seams | 12 pieces |
| Rows in the cutting plan | pieces laid across 140 cm of usable width, widest first, some pieces turned sideways | 4 rows |
| Fabric for the rows | 48 cm + 48 cm + 48 cm + 48 cm | 192 cm |
| Total fabric required | rows | 192 cm |
| Buy, rounded up (nearest 10 cm) | 192 cm rounded up to the next 0.1 m | 200 cm |

### Cutting plan

| Row | Pieces across | Width used | Row length |
| --- | --- | --- | --- |
| 1 | front + front + envelope back | 131 cm | 48 cm |
| 2 | front + front + envelope back | 131 cm | 48 cm |
| 3 | envelope back + envelope back + envelope back | 131 cm | 48 cm |
| 4 | envelope back + envelope back + envelope back | 131 cm | 48 cm |

## Assumptions

- Square or rectangular covers, front and back from the same fabric.
- A cover wider than the roll is refused, not seamed: a join across a cushion face is a defect.
- Piping strips are cut across the roll and are already a cut size, so they take no further allowance.
- Zips, cord, inserts and thread are not fabric and are not counted.

## Common questions

### What size should the cover be for my insert?

Make the cover 2–3 cm smaller in each direction than the insert. A cover cut to the same size as its pad hangs slack at the corners; one cut slightly under is filled out by the insert and holds a square, plump shape.

### Does an envelope back use more fabric than a zip?

Usually a little more cloth in total — two pieces of roughly 60% of the cover height each, against one piece the size of the front — but not always more length, because the two shorter pieces often pack into a row a full-size back would not fit. The calculator costs both and tells you which wins on your roll.

### How much fabric does piping need?

A 45 cm cushion needs about 1.9 m of piping, and strips are cut across the roll, so each strip yields one roll-width of piping and costs 4 cm of length. Four cushions therefore take six or seven strips — around 25 cm of fabric, which is why piping is the thing people most often run short of.

### Should piping strips be cut on the bias?

On a square cushion the straight grain is fine and costs less. Bias strips are for curves — round cushions, bolster ends, piped corners with a tight radius — and take about 41% more fabric because a diagonal strip covers less of the roll for the same length.

### What about a patterned fabric?

Each row of the cutting plan is rounded up to whole pattern repeats so the pieces line up down the roll, and one extra repeat is added so the first row can be placed where you want it. Centring a motif on every cushion face costs more than that, and is a layout decision made on the actual roll.

## Related tools

- [Fabric yardage calculator](https://fabricmeasure.com/calculators/fabric-yardage-calculator/): Piece size, how many, roll width — the length to buy, and the strip you pay for but never cut.
- [Upholstery fabric calculator](https://fabricmeasure.com/calculators/upholstery-fabric-calculator/): An editable panel list instead of a rule of thumb — with the cutting plan and the seams it implies.
- [Seam allowance calculator](https://fabricmeasure.com/calculators/seam-allowance-calculator/): Finished size to cut size — and what a different allowance does to the garment you end up with.
- [Seam allowance chart](https://fabricmeasure.com/charts/seam-allowance-chart/): Every common allowance in millimetres and inches, and which projects use which.
- [Bias binding calculator](https://fabricmeasure.com/calculators/bias-binding-calculator/): Straight-grain strips or one continuous bias strip from a square, costed side by side.
- [Pattern repeat calculator](https://fabricmeasure.com/calculators/pattern-repeat-calculator/): The cut length a repeat forces, what is trimmed from every piece, and what matching the design costs.