The Formula
°C = (°F − 32) × 5/9
Subtract 32 first, then multiply by 5 and divide by 9. The example above: 98.6 °F − 32 = 66.6, × 5/9 = 37 °C — the classic body-temperature pair. The order matters: subtracting 32 realigns the scales’ zero points (water freezes at 32 °F) before the 5/9 ratio corrects the degree size.
The Mental Shortcut
For weather, subtract 30 and halve it: 70 °F → (70−30)/2 = 20 °C (exact: 21.1). Exact at 50 °F = 10 °C, and within a couple of degrees across the everyday range. Another anchor style many people prefer: memorize that 68 °F is 20 °C and each 9 °F step is 5 °C — so 77 °F is 25 °C, 86 °F is 30 °C, 95 °F is 35 °C.
Reading American Weather and Recipes
US forecasts in the 30s °F mean around freezing (0–4 °C); 50s are cool (10–15 °C); 70s are pleasant (21–26 °C); 90s are hot (32–37 °C); “triple digits” (100 °F+) means 38 °C and up. In the kitchen, the standard American 350 °F oven is 177 °C — use 180 °C; 425 °F for roasting is ~220 °C.
Frequently Asked Questions
Is 100 degrees Fahrenheit hot?
As weather, yes — 100 °F is 37.8 °C, heat-wave territory. As body temperature it’s only slightly elevated: fever is usually flagged from 100.4 °F (38 °C).
What is 350 °F in Celsius for baking?
176.7 °C — set your oven to 180 °C. All standard US baking temperatures have rounded metric partners: 325 °F→160 °C, 375 °F→190 °C, 400 °F→200 °C, 425 °F→220 °C.
Why does the US still use Fahrenheit?
Inertia more than merit: the US never completed metrication, and Fahrenheit’s finer degrees map neatly onto human-comfort weather (0–100 °F covers most of the US climate). Science and medicine in the US use Celsius.
At what temperature are both scales equal?
−40. Solve (F − 32) × 5/9 = F and you get −40 — the single crossing point of the two scales, and a handy way to sanity-check any converter.