Brewing recipes and equipment mix Fahrenheit and Celsius depending on where they're published, and mash and fermentation temperatures are precise enough that converting by memory (or a rough "times two" shortcut) introduces real error — a couple of degrees off on a mash target genuinely shifts a beer's fermentability.
The conversion table
| °F | °C |
|---|---|
| 32 (freezing) | 0.0 |
| 60 | 15.6 |
| 65 | 18.3 |
| 66 | 18.9 |
| 68 | 20.0 |
| 70 | 21.1 |
| 75 | 23.9 |
| 90 | 32.2 |
| 100 | 37.8 |
| 152 (typical mash) | 66.7 |
| 154 | 67.8 |
| 158 | 70.0 |
| 168 (mash-out) | 75.6 |
| 212 (boiling) | 100.0 |
These figures come from the exact same °C = (°F - 32) x 5/9 conversion this site's strike water calculator runs internally on every input and output — not a rounded approximation, the live formula evaluated at each temperature shown.
The temperatures that actually matter on brew day
- 148-158°F (64.4-70°C) covers the practical mash-temperature range — see mash temperature and body for what different points in this range do to the finished beer's fermentability.
- ~168°F (75.6°C) is a typical mash-out temperature, used to halt enzyme activity before lautering.
- 60-75°F (15.6-23.9°C) covers most ale fermentation temperature ranges, and is also the range most hydrometers are calibrated to read accurately at — see hydrometer temperature correction if your gravity sample is read outside this band.
- 212°F (100°C) is sea-level boiling — actual boiling point drops at altitude, which matters more for boil vigour and evaporation rate than for any calculation on this site, but is worth knowing if you brew somewhere with meaningful elevation.
Using this alongside the calculators
Every temperature input on this site's strike water calculator takes Celsius directly, since that's the unit the underlying formula's constants are tuned to internally — but the tool converts and displays Fahrenheit results too, so you never have to do this conversion by hand mid-calculation. This chart is for cross-referencing a recipe or equipment spec written in the unit you don't normally think in, or for a quick sanity check that a converted number looks right before you commit it to a brew day.
A common rounding trap
Converting by a rough mental shortcut — doubling a Celsius figure and adding 30, or halving a Fahrenheit figure and subtracting 15 — gets close enough for casual conversation but drifts by a degree or two at the temperatures that matter most for brewing. At mash temperatures specifically, where a couple of degrees genuinely shifts fermentability, that drift is exactly large enough to matter: the difference between a 152°F and a 154°F mash target is only about 1.1°C, well inside the error a mental shortcut typically introduces. Use the exact formula, or this table, rather than a shortcut for anything you're actually going to act on.