EZGlassPattern · Free calculator

How much glass, foil and lead came do I need?

Enter your panel's size and how many pieces it has. The estimate updates as you type, and the arithmetic is below so you can check it.

Updated October 15, 2026

Width (in)

Height (in)

Pieces

Glass waste (%)

Glass to buy: 1.25 sq ft · 0.12 m²; 1.00 sq ft of pattern plus 25% for waste and breakage.
Copper foil: 26 ft; Every piece wrapped all round, plus 10%.

An estimate from size and piece count. For exact amounts per colour, measured from your real pieces, make a pattern or check one you have: the pattern packet's shopping list does it for you.

Answer in 30 seconds

Glass: the panel's area plus about 25% for waste. Copper foil: the total perimeter of every piece, plus 10%. Lead came: each inside seam once, plus the outside edge. A 12 × 12 in suncatcher with 30 pieces needs about 1.25 sq ft of glass and 26 ft of copper foil.

Glass: area × 1.25, worked out per colour when you shop.
Copper foil: about 4.3 × √(area × pieces), plus 10%. Every piece is wrapped all round, so seams count twice.
Lead came: (total piece perimeter − border) ÷ 2 of H came for the inside seams, plus the border.

Worked examples (copper foil, default allowances)

Panel	Pieces	Glass to buy	Copper foil	Lead came instead
12 × 12 in suncatcher	30	1.25 sq ft	26 ft	11 ft + 5 ft border
16 × 20 in panel	50	2.78 sq ft	50 ft	22 ft + 7 ft border
18 × 24 in panel	80	3.75 sq ft	74 ft	33 ft + 8 ft border
24 × 36 in window	150	7.50 sq ft	142 ft	66 ft + 11 ft border

Key takeaways

More pieces means more foil, not more glass — glass follows the area; foil and came follow the lines, which grow with the square root of the piece count.
Buy about 25% extra glass — for the gaps between pieces, the odd bad break, and matching streaky sheets. The guide range is 10 to 20% for experienced cutters.
Foil counts every seam twice — both pieces either side of a seam are wrapped. Lead came counts it once.
Round up to what's sold — sheet sizes, foil rolls and came lengths only come in steps, so buy the next size up.

Check a pattern, or make one from a photo.

How the estimate works

Glass is the panel's width × height, plus the waste percentage you set (25% by default, the same default as the shopping list in the EZGlassPattern pattern packet).

Copper foil is the sum of every piece's perimeter. Without the pattern in front of us, the calculator estimates it from the area and the piece count: if a panel of area A is cut into n roughly equal pieces, each has an area of A ÷ n, and a square of that area has a perimeter of 4 × √(A ÷ n). Real pieces are less tidy than squares. Measured on patterns EZGlassPattern makes from photos, the total comes out at about 4.3 × √(A × n), so that's the factor used. Then 10% is added for overlaps and offcuts.

Lead came runs along each seam once. The inside seams are the total perimeter minus the outside edge, halved (each seam was counted for both pieces). The border is the panel's outside edge, usually in U came or zinc.

When the estimate is off

Lots of long, thin or curvy pieces: more perimeter per piece, so more foil than the estimate. Add 10 to 20%.
A few big pieces and many small ones: the total perimeter is higher than for even pieces of the same count.
Several colours: the glass total is right, but you buy it per colour, and each colour needs a sheet big enough for its largest piece.
For exact amounts, make a pattern from a photo or check the pattern you have: the packet's shopping list measures every real piece and gives glass per colour, foil and came.

Step by step

1
Measure the finished size
Width and height of the panel at the size you will build it.
2
Count the pieces
Count the pieces on the pattern, or use the number you plan to make.
3
Work out the glass
Multiply width × height, then add your waste allowance (about 25%).
4
Work out the foil or came
Foil: 4.3 × √(area × pieces), plus 10%. Came: subtract the border from that perimeter and halve it, then add the border.
5
Round up
Round each amount up to the sheet sizes, foil rolls and came lengths your supplier sells.

Frequently asked questions

How much copper foil do I need per square foot?

It depends on the piece count more than the area. Using the estimate above, a 1 square foot panel needs about 22 ft of foil in 20 pieces and about 34 ft in 50 pieces.

What waste percentage should I allow for glass?

Experienced cutters often allow 10 to 20%. The calculator and the EZGlassPattern shopping list default to 25%, which leaves room for a beginner's bad breaks and for matching streaky glass. Change it in the calculator.

How much lead came do I need for a panel?

Inside seams once (the total piece perimeter, minus the border, halved), plus the outside edge, plus extra for joints and offcuts. The calculator shows both lengths when you choose lead came.

What foil width should I use for 3 mm glass?

7/32 inch foil is the usual choice for standard 1/8 inch (about 3 mm) glass. Go wider for thicker glass or a heavier solder line, narrower for fine detail. It doesn't change the length you need.

How much solder will I need?

The calculator doesn't estimate solder: it depends on how wide and high you run the bead, and whether you solder both sides. It scales with the same seam length as the foil, so a panel needing twice the foil needs roughly twice the solder.

Is the calculator free?

Yes, with no account. So are making a pattern and the cut check in EZGlassPattern; you only pay to print the full pattern packet.

The check is free. Pay once when you print.

No account and no card for the cut check. A Project Pass is $5 one-time for 30 days of printable pattern packets, with no subscription. Lifetime covers everything, forever.

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