Continuous Bias Binding Calculator
Bias strips run at 45°, so you cannot pull a long one straight off the roll; you cut a square on the diagonal and join it, or wind it as one continuous tube. What the length really fixes is an area: 300 cm × 4 cm = 1,200 cm², plus 10% for the joins and trimming, so √1,320 ≈ 36.3 cm square.
Your numbers
Cut width
36.3cm
Fabric needed
40cm
Formula
Cut width = √(Binding length × Strip width × 1.1)
Double-fold tape finishing 1 cm wide is cut four times that — 4 cm. Entering the finished width leaves nothing to fold under. Knits already stretch and rarely need bias-cut binding at all.
What to enter
| Input | Default | Accepted range |
|---|---|---|
| Binding length (cm)Binding to go round, including corners and joins. | 300 | 1 and up |
| Strip width (cm)Cut width of a binding strip — about four times the finished edge. | 4 | 0.5 and up |
Step by step
Quick reference table
Results when only Binding length (cm) changes and everything else stays put.
| Binding length (cm) | Cut width (cm) | Fabric needed (cm) |
|---|---|---|
| 150 | 25.7 | 30 |
| 225 | 31.5 | 40 |
| 300 | 36.3 | 40 |
| 450 | 44.5 | 50 |
| 600 | 51.4 | 60 |
What each result means
| Result | At default values |
|---|---|
| Cut width (cm)The width to cut — finished size plus allowance. | 36.3 |
| Fabric needed (cm)Fabric length to buy, along the grain rather than across. | 40 |
Common mistakes
Double-fold tape finishing 1 cm wide is cut four times that — 4 cm. Entering the finished width leaves nothing to fold under. Knits already stretch and rarely need bias-cut binding at all.
Glossary
- Binding length
- Binding to go round, including corners and joins.
- Strip width
- Cut width of a binding strip — about four times the finished edge.
- Cut width
- The width to cut — finished size plus allowance.
- Fabric needed
- Fabric length to buy, along the grain rather than across.
Frequently asked questions
Q. How is Continuous Bias Binding Calculator calculated?
Cut width = √(Binding length × Strip width × 1.1) — Bias strips run at 45°, so you cannot pull a long one straight off the roll; you cut a square on the diagonal and join it, or wind it as one continuous tube. What the length really fixes is an area: 300 cm × 4 cm = 1,200 cm², plus 10% for the joins and trimming, so √1,320 ≈ 36.3 cm square.
Q. Can you walk through an example?
With Binding length 300cm, Strip width 4cm, the answer is Cut width 36.3cm.
Q. What do I need to enter?
Enter Binding length, Strip width. 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 Binding length (cm) moves the answer to Binding length (cm) 150 → Cut width (cm) 25.7 and Binding length (cm) 600 → Cut width (cm) 51.4. 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?
Double-fold tape finishing 1 cm wide is cut four times that — 4 cm. Entering the finished width leaves nothing to fold under. Knits already stretch and rarely need bias-cut binding at all.
Related calculators
Materials differ in density and absorption. If your label states a figure, use it — the defaults here are only common values.