Window Blind Fabric Calculator
The blind fabric estimator calculates approximate fabric widths and total roll length from finished window dimensions, fullness, hems and fabric roll width.
How to use this calculator
- Enter finished width/drop in centimetres, fullness ratio, hem allowance per end and the fabric roll width.
- Check the units and definitions before comparing results with another source.
- Change one input at a time when comparing scenarios, and keep the reporting period and assumptions consistent.
Formula used by the window blind fabric calculator
Cut width = finished width × fullness; roll length = widths required × (drop + 2 × hem allowance)
- Cut width = finished width × fullness; roll length = widths required × (drop + 2 × hem allowance)
- Pattern repeat, nap direction, seams, brackets, fabric defects and manufacturing allowances may increase material needs.
- Inputs are checked for required values and valid ranges; displayed results are rounded for readability.
Worked examples
Worked example
A 180 cm blind width, 160 cm drop, 2× fullness, 10 cm hems at each end and 140 cm roll width.
Cut width is 360 cm, requiring three fabric widths; cut drop is 180 cm, giving about 5.4 m of fabric.
Cut width is 360 cm, requiring three fabric widths; cut drop is 180 cm, giving about 5.4 m of fabric.
Understanding the result
The blind fabric estimator calculates approximate fabric widths and total roll length from finished window dimensions, fullness, hems and fabric roll width.
Pattern repeat, nap direction, seams, brackets, fabric defects and manufacturing allowances may increase material needs.
Important notes
Pattern repeat, nap direction, seams, brackets, fabric defects and manufacturing allowances may increase material needs.
The result applies to the numbers and assumptions entered here; verify specifications for safety-critical or regulated uses.
Frequently asked questions
What does fullness ratio mean?
It is the amount of flat fabric width divided by the finished width, used here to estimate gathered fabric.
Why round widths up?
Fabric is usually purchased in complete roll-width cuts; the layout and pattern may demand even more.
How do I use this calculator?
Enter finished width/drop in centimetres, fullness ratio, hem allowance per end and the fabric roll width.
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Related explanations
Learn the method behind the number or compare the terminology before using the calculator.
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This page provides a calculation tool plus explanatory information so you can understand what the result means and when the underlying method may not fit your situation.