Window Treatment Calculator
Calculate curtain panels, fabric yardage, or blind dimensions for any window. Covers inside mount and outside mount installations.
Curtain Sizing Guide
The most important number in curtain sizing is the rod width, not the window width. Mount the rod 6–12 inches beyond the window frame on each side so curtains stack clear of the glass when open. A 36-inch window with a rod extending 8 inches on each side = 52-inch rod width. With 2x fullness, you need 104 inches of curtain coverage — two 54-inch panels.
| Window Width | Rod Width (8 in each side) | 2x Fullness Needed | Standard Panels |
|---|---|---|---|
| 24 in (2 ft) | 40 in | 80 in | 2 × 42 in panels |
| 36 in (3 ft) | 52 in | 104 in | 2 × 54 in panels |
| 48 in (4 ft) | 64 in | 128 in | 3 × 54 in panels |
| 60 in (5 ft) | 76 in | 152 in | 3 × 54 in panels |
| 72 in (6 ft) | 88 in | 176 in | 4 × 54 in panels |
| 96 in (8 ft) | 112 in | 224 in | 4–5 × 54 in panels |
Standard Curtain Lengths
| Length | Drop | Best For |
|---|---|---|
| 63 inches | To sill (for 8 ft ceilings, rod at 80 in) | Kitchen, casual spaces |
| 84 inches | Apron or near-floor (most common) | Bedrooms, living rooms |
| 96 inches | Floor length (for 9 ft ceilings) | Formal living rooms |
| 108 inches | Floor length (for 10 ft ceilings) | Formal dining, high ceilings |
| Custom | Exact floor or puddle | Made-to-measure drapes |
Inside vs. Outside Mount Blinds
| Mount Type | How to Measure | Best For |
|---|---|---|
| Inside mount | Exact window opening width and height — measure 3 points, use narrowest/longest | Clean look, deep window sills |
| Outside mount | Add 2–4 in each side for width; add 2–3 in above frame for height | Light blockage, shallow sills, privacy |
Frequently Asked Questions
How wide should curtains be for a window?
Curtains should be 1.5–3x the rod width for a full, gathered look. For a standard 36-inch window with rod extending 8 inches each side (52-inch rod), two 54-inch panels (108 inches total) gives a 2x fullness — the most common choice for living rooms and bedrooms.
How long should curtains be?
Floor-length curtains should fall within 0.5 inches of the floor for a tailored look. Measure from the rod to the floor, not from the window frame. Standard pre-made lengths are 63, 84, 96, and 108 inches — choose based on your ceiling height and rod placement.
How do I measure for inside mount blinds?
Measure the window opening width at the top, middle, and bottom — use the narrowest measurement. Measure height at left, center, and right — use the longest. Most blind manufacturers deduct a small amount from the width for proper fit; check the manufacturer's instructions.
What is the standard curtain rod placement height?
Mount the rod 4–6 inches above the window frame, or higher to make the room feel taller. Extend the rod 6–12 inches beyond the window frame on each side so curtains clear the glass when open and maximize natural light.