Adjusting Cooking Time When You Change the Oven Temperature
Lowering the oven temperature generally requires increasing cooking time, and raising it generally requires decreasing cooking time, but the relationship isn't a simple linear trade-off — a rough commonly used guideline is adjusting time by about 25% for each significant temperature change (roughly 25°F), though checking for doneness directly remains more reliable than relying purely on a time-adjustment formula.
This kind of adjustment comes up often — a different oven's calibration, a recipe from a different temperature convention, or a deliberate choice to cook at a different temperature than specified.
The general relationship
A lower oven temperature transfers heat to the food more slowly, requiring more time to reach the same level of doneness — conversely, a higher temperature cooks faster but risks the outside finishing (or burning) before the inside is fully cooked, especially for larger or denser items.
Why the adjustment isn't a simple linear formula
Heat transfer and cooking chemistry don't scale in a perfectly straightforward, linear way with temperature — a rough guideline like adjusting time by about 25% per 25°F change is a reasonable starting estimate, but it's an approximation, not an exact physical law, and different dishes (dense versus thin, wet versus dry) respond somewhat differently to the same temperature change.
Why checking doneness directly still matters
Given the imprecision of any time-adjustment estimate, checking actual doneness (internal temperature for meat, a toothpick test for baked goods, visual browning) remains the more reliable final check — treating an adjusted time as a starting estimate to check against, not a guaranteed exact endpoint, avoids under- or over-cooking based purely on an approximate formula.