Curtain Size Calculator

Adjust the calculator values below

Recommended rod or track span 48 in
Total flat curtain width 96 in
Flat width per panel 48 in
Width coverage beyond opening 6 in per side
Centre overlap allowance 0 in
Target curtain length 64 in
Header position above opening 4 in
Extension below opening 0 in
Number of panels 2
Planned panel size 48 in wide × 64 in long
2 panels: 48 in × 64 in each
Planned finished panel size Equal-panel sizing from opening dimensions, coverage extensions, fullness, and vertical placement
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Curtain Size Calculator

Use this curtain size with window opening width, window opening height, and coverage beyond opening per side to get fast results, understand the...

What this curtain size calculator plans

This calculator converts a measured window opening into a rod or track span and equal finished curtain-panel sizes. It adds the chosen horizontal coverage outside the opening, applies a fullness ratio to the covered span, adds any centre overlap, and divides the resulting flat width equally among the panels.

How curtain length is determined

Target curtain length is the window opening height plus the measured distance from the opening top to the curtain header and the measured extension below the opening. This supports sill, apron, floor, or other placements without imposing a fixed style offset; measure the actual intended top and bottom positions.

Finished size is not fabric yardage

The results are finished sizing targets, not cut dimensions or an amount of fabric to purchase. Heading take-up, hems, seams, shrinkage, fabric width, pattern repeat, lining, returns, and construction method add material beyond the finished dimensions. Use the Curtain Panel Calculator for a standard-roll yardage estimate, then confirm the hardware and sewing plan before ordering or cutting.

Frequently asked questions

Common questions about curtain size, useful assumptions, result interpretation, and mistakes to avoid.

What does curtain size mean?

Curtain Size describes a specific relationship between the values you enter, especially Window opening width and Window opening height. The result is useful when those values describe the same real-world case.

When is curtain size useful?

Curtain Size is useful when you need a quick estimate before comparing options, checking a document, planning a task, or explaining a number to someone else.

Which assumptions matter most for curtain size?

The most important assumptions are the ones behind Window opening width, Window opening height, units, timing, and scope. If those assumptions are wrong, recommended rod or track span can look precise but still be misleading.

How should I interpret curtain size?

Read recommended rod or track span with the inputs beside it. A high or low answer only makes sense after you know the unit, time period, comparison point, and any limits of the calculation.

Why might curtain size look different somewhere else?

Another tool may use different rounding, units, default assumptions, formulas, or boundaries. Compare the inputs before assuming either answer is wrong.

What mistake should I avoid with curtain size?

Avoid mixing values from different people, projects, dates, unit systems, or scenarios. The calculation works best when every input belongs to the same case.

What should I compare with curtain size?

Age Calculator can help with a nearby question when you want a second view of the same decision, measurement, or planning problem.