Sourdough Temperature Guide

Fermentation speed is temperature-dependent. A 4-hour bulk at 76°F becomes 6 hours at 68°F — and 3 hours at 82°F. Multipliers below from Modernist Bread vol 3.

Timing calculator

Multiplier at 76°F
Adjusted bulk ferment
4 h
Adjusted final proof
12 h
How the math works

Multipliers are piecewise-linear interpolations between reference points measured by Myhrvold et al. in Modernist Bread vol 3. 76°F is the baseline (1.0×); every 10°F drop roughly doubles fermentation time, and every 10°F rise roughly halves it.

8 temperature ranges

Source: Myhrvold et al., Modernist Bread vol 3 — fermentation temperature multipliers.