# Pattern repeat calculator

Matching a patterned fabric means every piece has to start at the same point in the design, so each cut length is rounded up to a whole number of pattern repeats: a 255 cm cut in a fabric with a 64 cm repeat becomes 256 cm, and the surplus is trimmed away. The calculator below works out the matched cut length, the fabric lost from every piece, one extra repeat for placing the first cut, and the total — alongside what the same pieces would take in a plain fabric, which is the true cost of the pattern.

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

---

## The formula

```
rawCutLength = pieceLength + allowances
repeats      = ceil(rawCutLength / patternRepeat)
cutLength    = repeats x patternRepeat
wastePerCut  = cutLength - rawCutLength
total        = cuts x cutLength + patternRepeat   (one repeat, for placement)
```

With patternRepeat = 0 there is nothing to match: cutLength = rawCutLength and no
placement allowance is added. Every rounding step rounds UP, never to nearest, and the
ceiling is epsilon-guarded so a cut length converted from inches cannot buy a spurious
extra repeat.

## Worked example

4 pieces finishing at 220 cm, 35 cm of allowances each, 64 cm vertical repeat.

| Step | Working | Result |
| --- | --- | --- |
| Cut length before matching | 220 cm finished + 35 cm allowances | 255 cm |
| Repeats each cut has to span | ⌈255 cm ÷ 64 cm⌉ | 4 repeats |
| Cut length matched to the repeat | 4 × 64 cm | 256 cm |
| Trimmed off every cut | 256 cm − 255 cm | 1 cm |
| Fabric for the cuts | 4 × 256 cm | 1024 cm |
| Pattern placement allowance | one extra repeat, so the first cut can start where you want in the design | 64 cm |
| Total fabric required | cuts + placement allowance | 1088 cm |
| Buy, rounded up (nearest 10 cm) | 1088 cm rounded up to the next 0.1 m | 1090 cm |

The same 4 pieces in a plain fabric would take 1020 cm; matching the design costs 68 cm.

## Assumptions

- A straight (not half-drop) vertical repeat. A half-drop needs an extra half repeat per width after the first.
- Every piece is the same finished length.
- The repeat on the label is exact; printed fabric can drift over several metres.
- The placement allowance is one repeat, enough to choose where the first cut starts.

## Common questions

### What is a vertical pattern repeat?

The distance up the roll before the design starts again, printed on the fabric label as the vertical or straight repeat. Measure from one point on a motif to the identical point on the motif above it — that distance, not the size of the motif, is what governs the cut length.

### Why is every cut rounded up to a whole repeat?

So that all the pieces begin at the same point in the design. Cut them to the exact length instead and each one starts wherever the previous cut happened to end, which puts the motifs at a different height in every piece — obvious at a glance across a pair of curtains or a run of blinds.

### Why add one extra repeat on top?

Because the roll is cut wherever the roll happens to be. Without a placement allowance you have to start the first piece at whatever point in the design the shop cut, which may put a motif half-way off the hem. One spare repeat buys the freedom to start where you choose.

### Is a large repeat always more expensive?

It is more wasteful per piece, but what matters is where your cut length falls against the repeat. A 200 cm cut in a 50 cm repeat wastes nothing, while a 205 cm cut in the same fabric wastes 45 cm on every piece. Lengthening a hem to absorb that surplus is usually free.

### What about a half-drop repeat?

A half-drop steps the design down by half a repeat between adjacent widths, so each width after the first needs an extra half repeat to bring it back into line. This calculator assumes a straight repeat, which is what most furnishing fabrics use, and warns you when the difference applies.

## Related tools

- [Curtain fabric calculator](https://fabricmeasure.com/calculators/curtain-fabric-calculator/): Track width, drop, fullness and pattern repeat in; metres or yards to buy out, with every allowance adjustable.
- [Roman blind fabric calculator](https://fabricmeasure.com/calculators/roman-blind-fabric-calculator/): Fabric and lining for a flat blind — no fullness, but the repeat still decides the cut.
- [Curtain fullness calculator](https://fabricmeasure.com/calculators/curtain-fullness-calculator/): How many widths each curtain needs at the fullness you want — and what whole widths really gather to.
- [Fabric width converter](https://fabricmeasure.com/conversions/fabric-width-converter/): Pattern written for one bolt width, fabric bought at another — work out the equivalent length.