Piping Strip Width Calculator
The strip wraps all the way round the cord, so what it has to cover is the circumference, not the diameter. A 5 mm cord measures π × 0.5 = 1.57 cm around, and with 1 cm of seam allowance on each side you cut a 3.57 cm strip — near enough the imperial rule of a 1.5 in (3.8 cm) strip for 1/8 in cord at a 1/2 in allowance. For length, a 200 cm seam plus 10% for joins and corners is 220 cm, and since cord is sold by the metre you buy 3 m.
Your numbers
Strip width
3.57cm
Binding length
220cm
Cord length
300cm
Formula
Strip width = π × Cord diameter ÷ 10 + 2 × Seam allowance, Binding length = Seam length × 1.1
Cut the strip on the bias at 45°. A straight-grain strip kinks on curves and corners, and piping is almost always going somewhere curved. Turning a required bias length into a square of fabric is the bias binding calculator's job. As the cord gets fatter the wrapping share outgrows the allowance, so recalculate rather than reusing an old width. If you buy ready-made piping, check that its flange matches your pattern's seam allowance — if it does not, the visible thickness at the seam changes. Cotton cord shrinks, so pre-wash the cord as well as the fabric.
What to enter
| Input | Default | Accepted range |
|---|---|---|
| Cord diameter (mm)Diameter of the piping cord; the strip width comes from its circumference. | 5 | 0.5 and up |
| Seam allowance (cm)Allowance on one edge; it is added on both, so twice over. | 1 | 0 ~ 5 |
| Seam length (cm)Total length of seam the thread has to cover; add several seams together. | 200 | 0 and up |
Step by step
Quick reference table
Results when only Cord diameter (mm) changes and everything else stays put.
| Cord diameter (mm) | Strip width (cm) | Binding length (cm) | Cord length (cm) |
|---|---|---|---|
| 2.5 | 2.79 | 220 | 300 |
| 3.75 | 3.18 | 220 | 300 |
| 5 | 3.57 | 220 | 300 |
| 7.5 | 4.36 | 220 | 300 |
| 10 | 5.14 | 220 | 300 |
What each result means
| Result | At default values |
|---|---|
| Strip width (cm)Cut width of a binding strip — about four times the finished edge. | 3.57 |
| Binding length (cm)Binding to go round, including corners and joins. | 220 |
| Cord length (cm)Cord to cut, per single cord. | 300 |
Common mistakes
Cut the strip on the bias at 45°. A straight-grain strip kinks on curves and corners, and piping is almost always going somewhere curved. Turning a required bias length into a square of fabric is the bias binding calculator's job. As the cord gets fatter the wrapping share outgrows the allowance, so recalculate rather than reusing an old width. If you buy ready-made piping, check that its flange matches your pattern's seam allowance — if it does not, the visible thickness at the seam changes. Cotton cord shrinks, so pre-wash the cord as well as the fabric.
Glossary
- Cord diameter
- Diameter of the piping cord; the strip width comes from its circumference.
- Seam allowance
- Allowance on one edge; it is added on both, so twice over.
- Seam length
- Total length of seam the thread has to cover; add several seams together.
- Strip width
- Cut width of a binding strip — about four times the finished edge.
- Binding length
- Binding to go round, including corners and joins.
- Cord length
- Cord to cut, per single cord.
Frequently asked questions
Q. How is Piping Strip Width Calculator calculated?
Strip width = π × Cord diameter ÷ 10 + 2 × Seam allowance, Binding length = Seam length × 1.1 — The strip wraps all the way round the cord, so what it has to cover is the circumference, not the diameter. A 5 mm cord measures π × 0.5 = 1.57 cm around, and with 1 cm of seam allowance on each side you cut a 3.57 cm strip — near enough the imperial rule of a 1.5 in (3.8 cm) strip for 1/8 in cord at a 1/2 in allowance. For length, a 200 cm seam plus 10% for joins and corners is 220 cm, and since cord is sold by the metre you buy 3 m.
Q. Can you walk through an example?
With Cord diameter 5mm, Seam allowance 1cm, Seam length 200cm, the answer is Strip width 3.57cm.
Q. What do I need to enter?
Enter Cord diameter, Seam allowance, Seam 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 Cord diameter (mm) moves the answer to Cord diameter (mm) 2.5 → Strip width (cm) 2.79 and Cord diameter (mm) 10 → Strip width (cm) 5.14. 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?
Cut the strip on the bias at 45°. A straight-grain strip kinks on curves and corners, and piping is almost always going somewhere curved. Turning a required bias length into a square of fabric is the bias binding calculator's job. As the cord gets fatter the wrapping share outgrows the allowance, so recalculate rather than reusing an old width. If you buy ready-made piping, check that its flange matches your pattern's seam allowance — if it does not, the visible thickness at the seam changes. Cotton cord shrinks, so pre-wash the cord as well as the fabric.
Related calculators
Materials differ in density and absorption. If your label states a figure, use it — the defaults here are only common values.