Gathering Ratio Calculator for Ruffles
Work out how much flat fabric a gathered or ruffled edge needs. Pick a fullness ratio, or enter the flat length you have and read back the ratio it gives.
How to size fabric for gathering
- Enter the finished length of the gathered edge in inches.
- Choose a fullness ratio, such as 2.5 to 1, or enter a flat length instead.
- Read the flat length to cut and the extra fabric the gathers use.
Examples
20 inch edge at a 2.5 to 1 ratio
Finished 20 in, ratio 2.5
Flat length 50 in, extra fabric 30 in
Frequently asked questions
What gathering ratio should I use?
About 2 to 1 gives a light gather, 2.5 to 1 a medium ruffle, and 3 to 1 a full, dense ruffle. Lighter fabrics can take a higher ratio without looking bulky.
How is the flat length calculated?
The flat length is the finished length multiplied by the fullness ratio. A 20 inch edge at a 2.5 ratio needs 50 inches of flat fabric, so 30 inches of extra fabric gets gathered in.
Can I enter the flat length I already have?
Yes. Enter the finished length and the flat length you have, and the tool divides them to show the fullness ratio that results, along with the extra fabric used.
Does the gathering thread length matter?
Only the flat length sets how much fabric you cut. Run the gathering stitches along that full flat length, then draw it up to match the finished length you entered.
Should I add seam allowance to this?
Yes, separately. This figure is the flat gathered length only. Add seam or hem allowance on the ends and edges as your pattern requires before cutting.
Related tools
Seam Allowance Calculator
Find the cut size of a sewing piece from its finished size plus seam allowance. Enter finished width, height and allowance to get the dimensions to cut.
Hem Allowance Calculator
Find the cut length to include hem and seam allowances. Enter the finished length, hem and seam allowance, and double fold option to get the length to cut.
Fabric Yardage Calculator
Find how many yards of fabric you need to cut a set of rectangular pieces. Enter piece size, quantity and bolt width to get rows and total yardage.
Bias Tape Calculator
Find how much continuous bias tape a fabric square makes. Enter the square size and strip width to get total tape length in inches and yards.
Blanket Yarn Calculator
Plan a blanket cast-on, rows and yarn. Enter the width, length and gauge to estimate stitches, total rows, yards and the skeins you need to buy.
Candle Cost Calculator
Work out the cost to make a candle. Add wax, fragrance, wick, container and other costs to get a per-candle total for pricing your candles.