# Curtain Size Calculator

URL: https://speedycalculator.com/calculators/everyday-life/curtain-size/
Last updated: 2026-10-25

> The curtain size calculator works out the curtain length for sill, apron, floor, café and extra-long styles and the curtain width for standard, deluxe and ultra fullness from your window size.

## Inputs

- Curtain style
- Fullness
- Window drop (top of frame to sill, apron or floor) (in, cm)
- Window width (including overlap) (in, cm)
- Rod allowance above frame (in, cm)

## Results

- Curtain length
- Total curtain width
- Width of each of two panels

## Formula

```
Length: sill/apron/floor = window drop + 4 in rod allowance (+ 6 in extra-long); café = half the window height
Width = window width (plus overlap) × fullness (2, 2.5 or 3)
```

## Explanation

Curtains are usually mounted 4–6 in above the window frame and extend 3–8 in beyond each side so they do not block light when open. Floor-length curtains should just kiss the floor; "puddled" curtains add 6 in or more.

### How to use the Curtain Size Calculator

- **Curtain style**
- **Fullness**
- **Window drop (top of frame to sill, apron or floor)**
- **Window width (including overlap)**
- **Rod allowance above frame**

Results update as you type, and every field accepts the units shown in its menu.

### How it works

Choose the curtain style and fullness, and enter the window height (from where the rod will go to the sill, apron or floor) and width.

### Tips

- Measure over thin clothing with a soft tape held snug but not tight, and keep the tape level all the way round.
- Take each measurement twice; if you are between sizes, the larger size is usually the safer choice.
- Size charts vary by brand and country – check the maker's own chart when it is available.
- For sewing projects, pre-wash fabric before cutting and buy 10% extra for shrinkage, pattern matching and mistakes.

### Common mistakes to avoid

- Mixing inches and centimetres between the tape and the size chart.
- Forgetting seam and hem allowances when cutting fabric.
- Measuring an old, stretched garment instead of your body.

### Inputs explained

FieldWhat to enterCurtain styleChoose one: Sill length, Apron length, Floor length, Café (half height) …FullnessChoose one: Standard (2×), Deluxe (2.5×), Ultra (3×)Window drop (top of frame to sill, apron or floor)Units: in, cmWindow width (including overlap)Units: in, cmRod allowance above frameUnits: in, cm

### What each result means

- **Total curtain width** = [Window width (including overlap)]×[Fullness]
- **Width of each of two panels** = [Total curtain width]÷2

### Example values

How the main result changes when **Window drop** changes and everything else stays at the example values above:

Window drop (top of frame to sill, apron or floor) (in)Curtain length (in)404460648084100104120124160164

## Worked example

Inputs — Curtain style: Floor length; Fullness: Standard (2×); Window drop (top of frame to sill, apron or floor): 80 in; Window width (including overlap): 48 in; Rod allowance above frame: 4 in.

Results — **Curtain length = 84 in**; Total curtain width = 96 in; Width of each of two panels = 48 in.

## FAQ

**How wide should curtains be?**
Two to three times the width of the window (including overlap) so they look full when closed.

**How high should a curtain rod be?**
About 4–6 in above the window frame, or halfway between frame and ceiling to make the window look taller.

**What length are standard ready-made curtains?**
63, 84, 95, 108 and 120 in in the U.S.

**What formula does the Curtain Size Calculator use?**
Length: sill/apron/floor = window drop + 4 in rod allowance (+ 6 in extra-long); café = half the window height.