What curtain fullness ratio should I use?

Pencil pleat curtains need 2-2.5x fullness. Pinch pleat (triple) needs 2-2.5x. Eyelet curtains need 1.5-2x. Tab top curtains need 1.5x. Wave heading needs 2x. More fullness gives a more luxurious look.

How do I measure the curtain drop?

Measure from the top of the track or bottom of the pole ring to where you want the curtain to finish. For sill length, measure to 1cm above the sill. For below sill, add 15cm. For floor length, stop 1cm above the floor.

What is pattern repeat and why does it matter?

Pattern repeat is the distance before a print repeats. Each fabric width must be cut so patterns match horizontally when joined. You need to round up the cut drop to the next full pattern repeat, which uses more fabric.

What are standard curtain hem and heading allowances?

Standard hem allowance is 15cm (for a double 7.5cm hem). Heading allowance is 8-15cm depending on the heading type. Pencil pleat tape needs 10cm, pinch pleat 15cm, and eyelet heading 10cm above the tape.

What width fabric should I use for curtains?

Most curtain fabrics are 137cm (54in) wide. Some are 280cm (110in) wide — these railroaded fabrics can be turned sideways so you may not need seams. Always check the fabric bolt width before calculating.

SewCalcs

Curtain Fabric Calculator — Curtain Yardage

Calculate fabric needed for curtains with fullness, pattern repeat and hem allowances.

Track / Pole Width

Full track length including returns

Finished Curtain Drop

Top of track to hem position

Fullness Ratio

Number of Curtains

Pattern Repeat

0 for plain fabric

Fabric Width

Hem Allowance

15cm for double 7.5cm hem

Heading Allowance

Fabric Price (optional)

How We Calculate This

Curtain fabric is calculated by working out the total gathered width, dividing by fabric widths, then multiplying by the cut drop adjusted for pattern repeat.

The formula

Total width = Track width × Fullness ratio

Fabric widths per curtain = ceil(Total width ÷ Curtain count ÷ Fabric width)

Cut drop = Finished drop + Hem allowance + Heading allowance

Adjusted drop = ceil(Cut drop ÷ Pattern repeat) × Pattern repeat

Fabric = Total widths × Adjusted drop

Frequently Asked Questions

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Last updated: February 2026

All calculations are estimates. Always verify quantities before cutting or purchasing fabric.