You are not the first baker stumbling about the unpredictable yield issue. There’s even one baker - Stella Parks of Serious Eats fame - that addresses exactly that in her article on construction gingerbread.

Her recipe is designed for one half-sheet pan at a thickness of 3/16 inches, which is roughly equal to your 4mm.

And we have at least one example of a project based on that recipe on the network, namely Catija’s Eliza Doolots Hat from a Winter Bash a few years back.

You are not the first baker stumbling about the unpredictable yield issue. There’s even one baker - Stella Parks of Serious Eats fame - that addresses exactly that in her article on construction gingerbread.

Her recipe is designed for one half-sheet pan at a thickness of 3/16 inches, which is roughly equal to your 4mm.

For 175g flour plus another roughly 220g of other ingredients, she gets 1000cm² of dough.

And we have at least one example of a project based on that recipe on the network, namely Catija’s Eliza Doolots Hat from a Winter Bash a few years back.