Curtain Size Calculator

Measure the pole or track—not the glass

Curtains cover the full pole or track, so measure that usable span rather than the window pane or recess. On a pole, exclude decorative finials. If the hardware is not fitted, a common plan is to extend it 15–30 cm past each side of the recess where wall space allows.

That extension lets curtains stack away from the glass, improving daylight and making the window feel wider. Check for nearby walls, cupboards and radiators before finalising the hardware position.

Use fullness to create the folds

Curtains need more fabric than the straight width they cover. Multiplying the pole by 2 gives a versatile standard fullness; 1.5× creates a relaxed result, while 2.5× creates deeper, richer folds.

Heading construction affects the ideal fullness. Eyelets often work around 1.5–2×, pencil pleats around 2×, and wave or pinch-pleat systems may have manufacturer-specific spacing. Use the calculator result as a shopping target, then check the product instructions.

Choose a drop that suits the room

Measure from the correct point on the hardware: usually the eye of a ring, the top of a track glider or the top edge of an eyelet curtain. Measure to the sill, just below the sill, or the floor depending on the intended finish.

For floor-length curtains, take measurements at the left, centre and right because floors and poles are not always perfectly level. Using the shortest distance helps avoid accidental dragging; add intentional puddling only when the fabric and room can tolerate it.

Before you buy

Common measuring mistakes

• Buying curtains equal to the window width and ending up with almost no folds when closed.
• Including decorative finials in the usable pole measurement.
• Measuring the drop from the wrong point for the chosen heading type.
• Assuming the width printed on ready-made packaging always describes the full pair rather than each panel.