Stained Glass Foil Length Calculator
Copper foil wraps around the edge of each glass piece, and every piece has a small overlap where the start and end meet, so the total runs a bit past the raw perimeter sum. Add the overlap share to the summed perimeters for total length, then divide by roll length and round up.
Your numbers
Foil needed
324cm
Rolls needed
1rolls
Formula
Foil needed = Total piece perimeter (cm) × (1 + Overlap share ÷ 100)
More pieces means more overlap waste overall. For curvy designs, budget 10%+ overlap.
What to enter
| Input | Default | Accepted range |
|---|---|---|
| Total piece perimeter (cm) (cm) | 300 | 10 and up |
| Overlap share (%)The overlap as a share of the smaller circle’s area. | 8 | 0 ~ 30 |
| Foil roll length (cm) (cm) | 3,300 | 100 and up |
Step by step
Quick reference table
Results when only Total piece perimeter (cm) (cm) changes and everything else stays put.
| Total piece perimeter (cm) (cm) | Foil needed (cm) | Rolls needed (rolls) |
|---|---|---|
| 150 | 162 | 1 |
| 225 | 243 | 1 |
| 300 | 324 | 1 |
| 450 | 486 | 1 |
| 600 | 648 | 1 |
What each result means
| Result | At default values |
|---|---|
| Foil needed (cm) | 324 |
| Rolls needed (rolls) | 1 |
Common mistakes
More pieces means more overlap waste overall. For curvy designs, budget 10%+ overlap.
Frequently asked questions
QHow is Stained Glass Foil Length Calculator calculated?
Foil needed = Total piece perimeter (cm) × (1 + Overlap share ÷ 100) — Copper foil wraps around the edge of each glass piece, and every piece has a small overlap where the start and end meet, so the total runs a bit past the raw perimeter sum. Add the overlap share to the summed perimeters for total length, then divide by roll length and round up.
QCan you walk through an example?
With Total piece perimeter (cm) 300cm, Overlap share 8%, Foil roll length (cm) 3,300cm, the answer is Foil needed 324cm.
QWhat do I need to enter?
Enter Total piece perimeter (cm), Overlap share, Foil roll length (cm). The result recalculates as you type, and an empty box counts as zero.
QHow much does the answer move if I change a number?
Changing only Total piece perimeter (cm) (cm) moves the answer to Total piece perimeter (cm) (cm) 150 → Foil needed (cm) 162 and Total piece perimeter (cm) (cm) 600 → Foil needed (cm) 648. The table below lays out five steps.
QHow 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.
QAnything to watch out for?
More pieces means more overlap waste overall. For curvy designs, budget 10%+ overlap.
Related calculators
Materials differ in density and absorption. If your label states a figure, use it — the defaults here are only common values.