Skirt Calculator

Free calculator · ruffles & gathers

Gathering Ratio Calculator

Enter the finished edge and pick a ratio. Get the strip length, how many strips to cut across your fabric and how many seams to join.

  • 1.5× to 3×
  • Strips across the bolt
  • Open or loop
Gouache illustration of fabric strips gathered at three different ratios

Your measurements

Units
Ratio
Edge
in
The length the ruffle is sewn to.
×
in
Finished height.
in
in
in
in
Seam allowance where two fabric widths are sewn together.
Strip length
120"
60" × 2×
Strips to cut
3
Last strip 34"
Cut height
5"
2 joining seams
Fabric to buy
1/2 yd
0.4 m

Strips across the fabric

Strip 1Strip 2Strip 3

Cut each strip selvage to selvage, then join them end to end.

  • Free, no sign-up
  • Runs in your browser
  • Counts joining seams
  • Inches or centimeters

How it works

Pick a ratio, cut the strips

  1. Hands measuring with a tape

    Step 1: Measure the edge

    Measure the finished edge the ruffle will be sewn to.

  2. Hands entering measurements

    Step 2: Choose the ratio

    1.5× for a soft gather, 2× for a classic ruffle, 2.5–3× for a full, frilly look.

  3. Hands gathering fabric

    Step 3: Cut and join

    Cut the strips across the fabric, join them end to end and gather to the edge.

Worked example

A ruffle for a 60" edge

Worked example

60" edge, 2×, 4" high

Finished edge
60"
Ratio
2×
Ruffle height
4"
Fabric width
44"
Open in calculator

Result

Strip length
120"
Strips
3
Joining seams
2
Cut height
5"
Buy
1/2 yd (0.4 m)

At 1.5× the same edge needs 3 strips; at 3× it needs 5. In metric, a 150.0 cm edge takes 0.4 m (1/2 yd).

The math

Edge × ratio

strip length = finished edge × ratio

Each strip spans the fabric width, minus a seam allowance at each joined end. Divide, round up, and the last strip is shorter.

Show the steps for the 60" example

Strip length: 60" × 2× = 120". That takes 3 strips across 44" fabric, joined with 2 seams; the last one is 34" long. Each strip is cut 5" high.

Tips

For even gathers

  • Two rows of stitches

    Sew two long basting rows inside the seam allowance and pull both bobbin threads together.

  • Quarter it

    Mark quarters on the strip and on the edge, then match them before you pull.

  • Fine fabrics go fuller

    Voile and chiffon look thin at 1.5×. Try 2.5× or 3× for lightweight fabrics.

  • A whole skirt?

    For a gathered skirt with a waistband or elastic, use the gathered skirt calculator.

Frequently asked questions

What gathering ratio should I use?

1.5× is subtle, 2× is the classic ruffle, 2.5× is full and 3× is very frilly. Heavier fabric needs less.

Why do strips go across the fabric?

Cutting across the width is the most efficient way to get long strips. The cross grain also gathers softly.

What does loop mean?

A loop ruffle goes all the way round, like a hem, so the last strip joins the first. That adds one seam.

Does the height include seam and hem?

Enter the finished height. The calculator adds the seam allowance and the hem to give the cut height.

Can I use this for a tiered skirt?

Yes, one tier at a time. The tiered skirt calculator does all tiers at once.

Ready to gather?

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