FREE MEASUREMENT TOOL · NO SIGN-UP
Curtain Length Calculator
Calculate curtain drop for sill, apron, floor, break, and puddle endpoints. Results update as you type and all assumptions stay visible.
CURTAIN SIZE CALCULATOR
What are you measuring?
72 in flat width per panel × 2
Uses your 2× fullness and 6 in side extension. Finished length is the measured hanging-point-to-endpoint value you entered.
Open the detailed calculatorMULTI-WINDOW PROJECT
Keep every window in one quantity sheet
Saved only in this browser unless you export the JSON file. Browser storage can be cleared and is not a backup.
Add a measured window to begin the project sheet.
METHOD
How the calculation works
Rod length starts with the window width plus the entered extension at both sides. Total flat curtain width equals that working length multiplied by the selected fullness, then divides across the panel count.
Finished length starts from the entered window height and rod-above-window distance, then adds the selected endpoint distance. Because real sill-to-floor distance varies, the detailed calculation keeps that assumption visible.
Ready-made alternatives compare the calculated drop with common retail examples. They are options to investigate, not guarantees of fit.
Estimate, then verify
Measure the actual window and selected product. Manufacturer dimensions, heading systems, fabric behavior, and pattern matching can change the result. These tools do not determine hardware strength, fixings, or a guaranteed fit.
SOURCE NOTES
What this page is based on
Measurements here combine mathematical results with labeled commercial conventions and design recommendations. Disagreements are kept as ranges rather than averaged into a false standard.
- BETYDLIG/RÄCKA/HUGAD buying guide — Measure your windowIKEA · reviewed 2026-09-11
Primary manufacturer guide: add at least 6 in each side, add 6 in above, and use 2–2.5× rod width for panel planning.
- MATILDA curtain product specificationsIKEA · reviewed 2026-09-11
Manufacturer product guidance presents 1.5×, 2×, and 2.5× rod/track-width options for light through extra-full looks.
- Buying curtainsJohn Lewis & Partners · reviewed 2026-09-11
Retailer/workroom guidance on pole extension, hanging references, sill/floor endpoints, ready-made metric ranges, and double fullness.