Curtain Panel Calculator

Find out how many ready-made curtain panels to hang, how many packs to buy and how full the curtains will look. Works in inches or centimeters.

Units

Inches Centimeters

Usable rod span (in)

The length of rod the curtains will slide along, between the brackets or end caps. Fractions such as 76 1/2 are fine.

Width on the product listing (in)

The width printed on the listing or label, for example 52.

What does that width describe?

Listings are not consistent. Check whether the width is for one panel or for all panels in the pack together.

The width of one panel The width of the whole pack (all panels together)

Panels in one pack

1 for a single panel, 2 for a pair.

Fullness

How much wider the flat fabric is than the rod span: 2 means twice as wide. This is a style choice; lower numbers look flatter, higher numbers look gathered. 2 is filled in as an example; change it if you prefer.

How will the curtains open?

In the middle, with the same number of panels on each side To one side

How the calculation works

Find the flat width of one panel. If the listing width covers the whole pack, divide it by the number of panels in the pack.
Multiply the rod span by your fullness to get the flat fabric width you need.
Divide that by the panel width and round up to whole panels.
If the curtains open in the middle, round up to an even number so both sides match.
Round the packs up, so you can see how many spare panels you will have. Spare panels are not hung automatically.
Fullness when hung = panels hung × panel width ÷ rod span.

Worked example

A 76 in rod, panels 52 in wide sold in packs of 3, fullness 2, opening in the middle: you need 76 × 2 = 152 in of flat fabric. 152 ÷ 52 = 2.92, so at least 3 panels; for an even split, hang 4. That means 2 packs (6 panels), 2 spare, and 4 × 52 ÷ 76 ≈ 2.74× fullness when hung.

What this calculator does not cover

Curved or bay tracks, corner windows and sewing your own curtains (fabric yardage).
Pre-pleated curtains sold by finished width.
Whether a rod or bracket can hold the weight, and whether the curtains block light or give privacy.
Curtain length. Measure that separately for the exact hardware you use.

Guides

Curtain width: per panel or per pair? How to read the width on a listing.
How to measure for curtains: rod span, drop and the listing, in order.
Curtain length: 84, 96 or 108 inches? With a length check.

Source

Comparing the panels' flat width with the rod span multiplied by a chosen fullness follows retailer measuring guidance such as the IKEA US window guide (PDF). The product's own listing and instructions always take priority.