Fabric Calculator
Estimate how much fabric a sewing project needs for your size and fabric width.
Last updated · View algorithm, constants and default inputs (JSON)
About this calculator
A rough fabric-buying estimate based on garment, size and bolt width; it is not a pattern-specific cutting plan. Yardage lookups and size factors are assumptions. Check the pattern envelope and layout, especially for directional prints, nap, matching repeats or larger pattern pieces.
Worked example
calculated with the default values below
What are you making Dress · Size Medium · Fabric width 45 in · Extra fabric for matching or mistakes 0.25 yards · Price per yard 8 $ Yards needed at 45 inch width 3.25 yards · Yards needed at 60 inch width 2.50 yards · Yards to buy at your width 3.25 yards · Fabric cost 26.00 $ · Metres to buy 2.97 m
General background references
Disclaimer
These calculators provide planning estimates only. Building codes, wiring regulations and safety requirements differ by country and change over time, and nothing here replaces a licensed professional or a permit. For structural, electrical or gas work, follow local code and have the installation inspected.
Implementation source
This record describes the implementation used by this page. It is not independent validation. External references, when available, support only the stated formula or definition; estimates and custom rules retain their own assumptions.
Formula and variables
y45 = b45 × k; y60 = b60 × k; Y = { y60, w ≥ 58; (y45 + y60) ÷ 2, 50 ≤ w < 58; y45, w < 50 } + e
- b45
- garment base yards, 45 in width
- b60
- garment base yards, 60 in width
- k
- size factor
- w
- fabric width (in)
- e
- extra yards
- y45
- adjusted yards, 45 in width
- y60
- adjusted yards, 60 in width
- Y
- yards to buy
Base yardage and size factors are illustrative lookup assumptions, not a universal pattern standard. Under 50 in uses the 45-in estimate; 50–57.99 in linearly averages 45- and 60-in estimates; 58 in and wider uses the 60-in estimate. Add allowance for print matching and layout.
Frequently asked questions
How does fabric width change the estimate?
The model uses the 45-inch yardage below 50 inches, averages the 45- and 60-inch estimates from 50 to under 58 inches, and uses the 60-inch estimate at 58 inches or wider. These are lookup assumptions, not a pattern standard; check the pattern envelope and add allowance for matching repeats, nap and layout.