One sheet of the streaky blue, or two?
Give it the pattern's square inches per color, the piece count, and an average perimeter — it hands back sheets to buy, foil off the roll, and a solder estimate before you score a single line. Everything stays in your browser.
The glass, by color
Foil & solder
The numbers here are yours to check. This page does arithmetic on what you type — it cannot see your recipe, your equipment or your batch.
Want it to remember?
In MadeKeeper this same panel consumes its square inches per color from your sheet inventory, pulls foil yards off the roll and solder by the pound, and lands in the ledger as a real materials cost per panel — the number your price stands on. See for stained glass artists or poke around the live demo. $19/mo for the whole back office, kept for as long as you stay. The shop stays free for cost a piece and one fair — no product cap. The tax packet, Etsy and Square, and more fairs are the $19.
Free tool — no signup
The formulas here are the craft's own folk math, written down honestly — and every number the bench argues about is a setting you can move, not a constant we decreed.
How much extra glass should I actually buy?
Somewhere between 25 and 50 percent over your pattern's area — and where you land in that range is the most argued number in the craft, which is exactly why it's a setting here, defaulting to 30, not a constant. A workhorse opalescent that cuts happily in any direction lives near 25; a streaky or wispy sheet where every piece has to sit right on the grain can honestly eat 50. It compounds fast: 180 square inches of pattern at 30 percent is 234 to buy, and since a 12 by 12 sheet is only 144, that streaky blue is two sheets, not one. Your scrap bin knows your real number better than any default — set it, and the calculator uses yours.
Why does the foil estimate count shared edges twice?
Because both pieces genuinely wrap their own edge before they ever meet — foiling is per piece, so the estimate is piece count times average piece perimeter, full stop. Forty pieces averaging 9 inches around is 360 inches, or 10 yards, which one standard 36-yard roll covers with plenty left. Roll length is a setting since rolls vary, and changing foil width doesn't change the yardage you need — it changes which roll it comes off, which is what you're really asking mid-project.
How does it turn foil into a solder estimate?
In two admitted approximations. Seam feet is taken as the foiled perimeter divided by two, because an interior edge that two pieces both foiled gets one shared bead — your border treatment nudges that a little either way. Then the community estimate of about a pound of solder per 12 feet of beaded seam turns feet into pounds: the worked panel's 10 yards of foil is 30 feet of foiled edge, call it 15 seam feet, roughly 1.3 pounds. That pound-per-12-feet figure is a setting, not a law — if your last panel weighed in differently, your last panel wins.
What about lead and solder safety?
Deliberately not covered — in either direction. This tool does length and area arithmetic, and nothing on this page should be read as guidance about handling lead, solder, flux, or fumes. That conversation belongs to your own setup and your suppliers' documentation, which know your materials and your bench in ways a calculator never will.