Gathering Ratio Calculator for Ruffles

About 2 to 1 gives a light gather, 2.5 to 1 a medium ruffle, and 3 to 1 a full, dense ruffle. Those three are one-tap presets in the tool. Lighter, drapier fabrics can take a higher ratio without looking bulky, while stiff fabric looks fuller at a lower one.

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. The extra fabric tile always shows flat length minus finished length.

Yes. Click By flat length, 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. It is the quickest way to check whether a remnant is full enough.

It works in inches, which is what the fields and the suffix labels show. The math is a pure ratio, so if you prefer centimeters you can enter your numbers in centimeters and simply read every result as centimeters instead.

Only the flat length sets how much fabric you cut. Run the gathering stitches along that full flat length, then draw the fabric up until it matches the finished length you entered before you pin and sew.

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 you cut, since the calculator does not include any.

It works for any gathered edge, since fullness is the same idea at any scale. For a very long ruffle you may need to piece several fabric widths together to reach the flat length, so add seam allowance for each join.

Both add fullness, but pleats fold at fixed intervals while gathers bunch evenly. A knife-pleated edge is often calculated at a 3 to 1 ratio too, so this tool can ballpark simple pleating, though exact pleat math depends on pleat depth and spacing.

Yes. The calculation runs entirely in your browser, so the lengths and ratios you enter never leave your device and nothing is sent to a server.