Gathering Ratio Calculator
The gather ratio is how many times the finished length you cut before drawing it up. Two times a 60 cm opening means cutting 120 cm and gathering it back to 60, so 60 cm disappears into the folds. Fine fabrics take 2.5–3×, heavy ones stop near 1.5× — the same ratio reads as a completely different volume depending on the cloth.
Your numbers
Fabric needed
120cm
Extra to buy
60cm
Formula
Fabric needed = Finished length × Gather ratio
Fix the ratio before cutting: pulling the gathering thread cannot add length later. Ruffles and frills use the same arithmetic, usually at 2× or more.
What to enter
| Input | Default | Accepted range |
|---|---|---|
| Finished length (cm)The length when finished. | 60 | 1 and up |
| Gather ratio (×)How many times the finished length you cut; twice gives a full gather. | 2 | 1 ~ 5 |
Step by step
Quick reference table
Results when only Finished length (cm) changes and everything else stays put.
| Finished length (cm) | Fabric needed (cm) | Extra to buy (cm) |
|---|---|---|
| 30 | 60 | 30 |
| 45 | 90 | 45 |
| 60 | 120 | 60 |
| 90 | 180 | 90 |
| 120 | 240 | 120 |
What each result means
| Result | At default values |
|---|---|
| Fabric needed (cm)Fabric length to buy, along the grain rather than across. | 120 |
| Extra to buy (cm)The extra to buy so shrinkage does not leave you short. | 60 |
Common mistakes
Fix the ratio before cutting: pulling the gathering thread cannot add length later. Ruffles and frills use the same arithmetic, usually at 2× or more.
Glossary
- Finished length
- The length when finished.
- Gather ratio
- How many times the finished length you cut; twice gives a full gather.
- Fabric needed
- Fabric length to buy, along the grain rather than across.
- Extra to buy
- The extra to buy so shrinkage does not leave you short.
Frequently asked questions
Q. How is Gathering Ratio Calculator calculated?
Fabric needed = Finished length × Gather ratio — The gather ratio is how many times the finished length you cut before drawing it up. Two times a 60 cm opening means cutting 120 cm and gathering it back to 60, so 60 cm disappears into the folds. Fine fabrics take 2.5–3×, heavy ones stop near 1.5× — the same ratio reads as a completely different volume depending on the cloth.
Q. Can you walk through an example?
With Finished length 60cm, Gather ratio 2×, the answer is Fabric needed 120cm.
Q. What do I need to enter?
Enter Finished length, Gather ratio. The result recalculates as you type, and an empty box counts as zero.
Q. How much does the answer move if I change a number?
Changing only Finished length (cm) moves the answer to Finished length (cm) 30 → Fabric needed (cm) 60 and Finished length (cm) 120 → Fabric needed (cm) 240. The table below lays out five steps.
Q. How are the numbers rounded?
Money is shown to the nearest whole unit, percentages to one decimal place and everything else to two. What you see is rounded; the calculation itself carries the unrounded value forward.
Q. Anything to watch out for?
Fix the ratio before cutting: pulling the gathering thread cannot add length later. Ruffles and frills use the same arithmetic, usually at 2× or more.
Related calculators
Materials differ in density and absorption. If your label states a figure, use it — the defaults here are only common values.