Scale by area, keep depth
The multiplier is the ratio of pan areas. Keeping the batter at the same depth as the original recipe keeps the bake time close to what the recipe says.
If the new pan is much deeper or shallower than the original, start checking for doneness early and use a skewer.
Frequently Asked Questions
Does this account for pan height?
No. It compares footprint only. For loaf and bundt tins, compare volume instead.