# Roman blind fabric calculator

A Roman blind is a flat panel, so unlike a curtain it takes no fullness: the cloth across is the finished width plus a side turning at each edge, and a width is only joined when the blind is wider than the roll. Down the roll the cut is the finished drop plus an allowance to wrap the top batten and a hem deep enough to take the bottom bar, rounded up to whole pattern repeats on a patterned fabric. Lining is cut to the same length plus whatever the rod pockets consume.

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

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## The formula

```
A roman blind is FLAT. There is no fullness.

widths across = ceil so that
    W x fabric width - 2 x side turning - (W-1) x 2 x seam >= finished width
cut length = finished drop + allowance over the batten + bottom hem
if patterned: cut length = ROUND UP to a whole number of pattern repeats
total = widths x blinds x cut length  (+ one repeat to place the first cut)
total, ROUNDED UP to the cut increment

lining cut = finished drop + batten allowance + hem + pockets x pocket allowance
```

Side turnings are charged to the two OUTER edges only; every join between widths
costs two seam allowances instead. Rod pockets are carried by the LINING, so they
add to the lining length and nothing to the face fabric.

## Defaults

- Side turning: 5 cm per side
- Allowance over the batten: 10 cm
- Bottom hem: 12 cm (deep enough to take the bottom bar)
- Seam allowance: 1.5 cm
- Lining used per rod pocket: 3 cm
- Lining width: 137 cm
- Cut increment: Nearest 10 cm (Most UK and European shops cut roll goods to the nearest 10 cm.)

UK workroom middle-of-the-range, not a standard. Every one is editable on the page.

## Worked example

120 cm x 160 cm blind, plain 140 cm fabric, lined, 4 rod pockets.

| Step | Working | Result |
| --- | --- | --- |
| Widths across | 120 cm finished + 10 cm of side turnings, on 140 cm cloth | 1 width |
| Cut length before matching | 160 cm drop + 10 cm over the batten + 12 cm hem | 182 cm |
| Fabric required | 1 cut × 182 cm | 182 cm |
| Lining required | 1 × (182 cm + 4 pockets × 3 cm) | 194 cm |

Buy: 1.9 m of fabric, 2 m of lining.

## Not modelled

- FOLD DEPTH AND ROD SPACING. Published workroom methods disagree about how the
  bottom section relates to the folds above it, so no position is asserted. As a
  guide only: aim for a fold of 20-30 cm.
- Half-drop repeats: each extra width needs an additional half repeat.
- Cascade and relaxed blinds, which hold a permanent fold and need more length.
- Selvedge loss: the roll width is taken as entered.

## Common questions

### How much fabric do I need for a Roman blind?

The finished drop plus about 22 cm of allowances — roughly 10 cm to wrap the batten and 12 cm for a hem deep enough to take the bottom bar — by the finished width plus a turning each side. On a plain fabric that is the whole answer for a blind narrower than the roll. On a patterned fabric the cut is then rounded up to a whole number of repeats, which can add a great deal.

### Does a Roman blind need extra fabric for fullness?

No. That is the main difference from a curtain. A Roman blind hangs flat against the window and pleats only when it is drawn up, so the cloth across is the finished width and nothing more. A curtain at 2× fullness needs twice its track width; a blind of the same width needs one width of cloth.

### Where should the seam go if the blind is wider than the fabric?

A seam down a Roman blind is visible whenever the blind is down, which is most of the time. Standard workroom practice is a full width in the centre with equal part-widths joined either side, so the two seams sit symmetrically. A single seam falling near the middle of the blind is the arrangement to avoid.

### How many folds should a Roman blind have?

As a guide, aim for a fold of 20 to 30 cm — so a 160 cm blind usually takes five or six. This calculator allows for the lining each rod pocket consumes but does not tell you where the rods go: published workroom methods differ on how the bottom section relates to the folds, and the figures on this site are meant to be checkable against a source.

### Do I need lining for a Roman blind?

Almost always. The lining carries the rod pockets and the rings, protects the face fabric from sunlight, and gives the blind enough body to fold cleanly. Set the lining width to 0 in the calculator for an unlined blind, which is worth considering only on a heavy fabric where the folds will hold anyway.

## 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.
- [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.
- [Curtain lining calculator](https://fabricmeasure.com/calculators/curtain-lining-calculator/): Lining on its own narrower roll, from the flat width your curtains already need.
- [Fabric width chart](https://fabricmeasure.com/charts/fabric-width-chart/): Standard roll widths in both systems, and the gap between the label and the cloth.
- [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.