How many folds should a roman blind have?

Most roman blinds have 3-8 folds depending on the drop. A good rule is one fold every 20-25 cm. Short blinds (100 cm) suit 3-4 folds. Tall blinds (200 cm+) look best with 6-8 folds.

What is the difference between inside and outside mount?

Inside mount fits within the window recess for a clean look but requires precise measurements. Outside mount overlaps the window frame, covering more light gaps. Add 5 cm each side and 10-15 cm at the top for outside mount.

Do I need lining for a roman blind?

Lining is recommended for most roman blinds. It protects the face fabric from sun damage, improves the view from outside, adds body for neater folds, and helps block light. Use blackout lining for bedrooms.

What size dowels do I need?

Use 6mm or 8mm fibreglass rods or wooden dowels. They should be 2-3 cm shorter than the finished blind width. Fibreglass is preferable as it does not warp in humidity.

How much cord do I need?

Each cord column needs the full drop length plus the width of the blind (to run across to the operating side) plus 30 cm for the cord tail. Multiply by the number of cord columns (usually 3).

SewCalcs

Roman Blind Calculator — Fabric for Roman Blinds

Calculate fabric, lining, dowels, rings and cord for roman blinds.

Window Width

Finished blind width — for an inside recess, measure the narrowest point of the recess

Window Drop

Finished blind drop, top of the headrail to the sill

Number of Folds

Roughly one fold every 20-25 cm of drop

Fabric WidthUsable width of your fabric roll — wider blinds need widths joined

Include Lining

Recommended for all roman blinds

MountingInside recess fits inside the window; outside mount overlaps the frame (adds 5 cm each side, 15 cm top)

How We Calculate This

Roman Blind Fabric Calculation

Cut Width = Blind Width + (Side Hem × 2)

Cut Drop = Blind Drop + Bottom Hem + Heading + Rod Pocket Allowances

Roman blinds hang flat (no fullness), so if the cut width is wider than your fabric roll the calculator joins extra widths — Widths Joined = round up (Cut Width ÷ Fabric Width) — and multiplies the metres accordingly.

Traditional rod pockets are made from the lining, so the lining is cut to the same drop as the face fabric. The fold sizes follow the standard rule of equal full folds plus a half-depth bottom fold (Full Fold = Blind Drop ÷ (Folds − ½)).

Frequently Asked Questions

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Last updated: February 2026

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