Jelly Roll Quilt Calculator
A jelly roll is 40 strips of 2.5 in (6.4 cm) cut across a 42 in (107 cm) width. Sewing them together takes 1/4 in off each long edge, so one strip finishes 5.2 cm wide by 105.8 cm long. Joined side by side, 40 of them make 208 × 105.8 cm — an area of 2.2 m².
Your numbers
Pieced area
2.2m²
Quilt width
208cm
Quilt length
105.8cm
Formula
Pieced area = Strips in the roll × (Precut strip width − 1.2) × (Strip length − 1.2) ÷ 10000
Sewn straight together the strips give a short, wide panel 208 cm across. For a bed size, cut it in half and rejoin (104 × 211 cm), or piece a long strip set and crosscut it. The narrower the strip, the more of it the seams eat: 19% at 6.4 cm, 32% at 3.8 cm (1.5 in).
What to enter
| Input | Default | Accepted range |
|---|---|---|
| Strips in the rollHow many strips the bundle holds; a jelly roll is usually 40. | 40 | 1 and up |
| Precut strip width (cm)The precut strip as cut — 2.5 in is the jelly roll standard. | 6.4 | 1 and up |
| Strip length (cm)One strip end to end; cut across the bolt it runs about 42 in. | 107 | 1 and up |
Step by step
Quick reference table
Results when only Strips in the roll changes and everything else stays put.
| Strips in the roll | Pieced area (m²) | Quilt width (cm) | Quilt length (cm) |
|---|---|---|---|
| 20 | 1.1 | 104 | 105.8 |
| 30 | 1.65 | 156 | 105.8 |
| 40 | 2.2 | 208 | 105.8 |
| 60 | 3.3 | 312 | 105.8 |
| 80 | 4.4 | 416 | 105.8 |
What each result means
| Result | At default values |
|---|---|
| Pieced area (m²)The area left once the strips are sewn, with the seams taken out. | 2.2 |
| Quilt width (cm)The finished quilt across, once bound. | 208 |
| Quilt length (cm)The finished quilt along, once bound. | 105.8 |
Common mistakes
Sewn straight together the strips give a short, wide panel 208 cm across. For a bed size, cut it in half and rejoin (104 × 211 cm), or piece a long strip set and crosscut it. The narrower the strip, the more of it the seams eat: 19% at 6.4 cm, 32% at 3.8 cm (1.5 in).
Glossary
- Strips in the roll
- How many strips the bundle holds; a jelly roll is usually 40.
- Precut strip width
- The precut strip as cut — 2.5 in is the jelly roll standard.
- Strip length
- One strip end to end; cut across the bolt it runs about 42 in.
- Pieced area
- The area left once the strips are sewn, with the seams taken out.
- Quilt width
- The finished quilt across, once bound.
- Quilt length
- The finished quilt along, once bound.
Frequently asked questions
Q. How is Jelly Roll Quilt Calculator calculated?
Pieced area = Strips in the roll × (Precut strip width − 1.2) × (Strip length − 1.2) ÷ 10000 — A jelly roll is 40 strips of 2.5 in (6.4 cm) cut across a 42 in (107 cm) width. Sewing them together takes 1/4 in off each long edge, so one strip finishes 5.2 cm wide by 105.8 cm long. Joined side by side, 40 of them make 208 × 105.8 cm — an area of 2.2 m².
Q. Can you walk through an example?
With Strips in the roll 40, Precut strip width 6.4cm, Strip length 107cm, the answer is Pieced area 2.2m².
Q. What do I need to enter?
Enter Strips in the roll, Precut strip width, Strip length. 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 Strips in the roll moves the answer to Strips in the roll 20 → Pieced area (m²) 1.1 and Strips in the roll 80 → Pieced area (m²) 4.4. 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?
Sewn straight together the strips give a short, wide panel 208 cm across. For a bed size, cut it in half and rejoin (104 × 211 cm), or piece a long strip set and crosscut it. The narrower the strip, the more of it the seams eat: 19% at 6.4 cm, 32% at 3.8 cm (1.5 in).
Related calculators
Materials differ in density and absorption. If your label states a figure, use it — the defaults here are only common values.