How to use your swatch measurements
Mark and measure a representative piece along the fabric's length and width before washing. Use the care process you intend to use for the finished item, then measure the same marked distances after the sample has dried and settled. Record each direction separately: a fabric can change by different amounts along its length and across its width. These measurements describe your sample and care process; they do not predict an unknown fabric.
Calculate the length to start with
Enter the length you need after washing. The planner divides that length by the sample's retained length ratio. If a 20 cm marked length becomes 19 cm, the ratio is 0.95. A finished length of 300 cm therefore needs approximately 315.79 cm before washing. Adding only 5% to 300 cm would give 315 cm, which falls short after a 5% change.
The extra cutting allowance is separate from measured shrinkage. A 5% allowance on that compensated length gives approximately 331.58 cm. Choose an allowance appropriate to your work; there is no universal allowance in this tool. Displayed planning lengths round upward to the next 0.01 unit. Intermediate calculations use the unrounded measurements.
Check whether the width will still fit
Enter both the usable bolt width before washing and the required finished width for a width comparison. With width measurements of 20 cm before and 18 cm after, a 145 cm usable bolt width is estimated to become 130.5 cm. A 120 cm finished width fits with 10.5 cm to spare. Buying more length does not fix a continuous-width shortage; check the pattern or construction before buying.
Use usable width rather than a nominal bolt label if selvedges or defects reduce the area you can cut. This comparison does not arrange pattern pieces, calculate joins, or allow for nap, repeats, seam allowances, hems, defects or cutting waste. Include those separately in your required dimensions or cutting allowance, as appropriate.
Understand changes and limits
Positive percentages mean shrinkage. Negative percentages mean expansion; the calculation accepts a measured increase rather than silently replacing it with zero. Area change combines both measured direction ratios and is not a fabric weight or quality measurement. The estimate assumes those ratios apply consistently to the planned piece.
Check measurement accuracy and repeat the sample test when results look surprising. Results are planning estimates, not a guarantee of whole-bolt behavior or a textile testing certification. Measurements can vary with fabric, batch, treatment and measurement conditions. Test a representative sample before making an irreversible cut.
Units and temporary inputs
Choose centimetres or inches before entering measurements, or switch units to convert the entered dimensions. The conversion is exactly 2.54 centimetres per inch. The percentage allowance stays unchanged. Blank optional widths produce a length-only plan; a single width entry needs its matching field. No account, upload or stored history is used. Keep a separate record if you need to retain a plan.