Temperature Converter: °F to °C, Kelvin, Rankine

How to use the converter

Enter the temperature. Negative values and decimals are fine, such as −12.5.
From: the scale of your reading (°F, °C, K or °R).
To: the scale you want.

The result comes with the formula for that pair of scales and a table with the temperature on every scale. Values below absolute zero (0 K, which is −459.67 °F or −273.15 °C) are physically impossible, so the converter rejects them.

Formulas

Temperature scales don't just differ in size, they also start at different zero points, so you can't convert with a single multiplier. The converter first turns your value into kelvin, the SI unit, then into the target scale:

°C = (°F − 32) × 5/9 and °F = °C × 9/5 + 32
K = °C + 273.15
°R = K × 9/5, which is the same as °R = °F + 459.67

A step of 1 °C equals a step of 1 K, and a step of 1 °F equals 1 °R; each Celsius or kelvin degree is 1.8 times a Fahrenheit or Rankine degree. Between 32 °F (0 °C) and 212 °F (100 °C), roughly where water freezes and boils at sea level, there are 180 Fahrenheit degrees but only 100 Celsius degrees. Results are rounded to 12 significant digits, and leftover rounding noise near zero is cleared: −17.7777777778 °C converts to exactly 0 °F.

Examples

1. Oven temperatures

°F	°C (exact)	°C (rounded)
300 °F	148.9 °C	150 °C
325 °F	162.8 °C	160–165 °C
350 °F	176.7 °C	175–180 °C
375 °F	190.6 °C	190 °C
400 °F	204.4 °C	200–205 °C
425 °F	218.3 °C	220 °C
450 °F	232.2 °C	230 °C

A European recipe at 180 °C means 356 °F, and 200 °C is 392 °F.

2. Food safety

FoodSafety.gov lists a refrigerator at 40 °F or below (4.4 °C) and a freezer at 0 °F (−17.8 °C). Its safe minimum internal temperatures convert to 73.9 °C for poultry and leftovers (165 °F), 71.1 °C for ground meat (160 °F) and 62.8 °C for whole cuts of beef, pork, veal and lamb (145 °F, plus a 3-minute rest).

3. Body temperature and weather

The classic 98.6 °F equals 37 °C, 100.4 °F is 38 °C and 102 °F is 38.9 °C. For forecasts: −10 °C is 14 °F, 10 °C is 50 °F, 20 °C is 68 °F, 30 °C is 86 °F and 40 °C is 104 °F. At −40 the two scales meet: −40 °C is −40 °F.

Kelvin and Rankine

Kelvin and Rankine are absolute scales: zero is absolute zero, so they never go negative. Kelvin is the SI unit used in science and is written without a degree sign (293.15 K, not °K). Rankine is its counterpart with Fahrenheit-sized degrees: a room temperature of 20 °C is 293.15 K, 68 °F or 527.67 °R.

Frequently asked questions

How do I convert Fahrenheit to Celsius?

Subtract 32, then multiply by 5/9. For 72 °F: (72 − 32) × 5/9 = 22.2 °C.

How do I convert Celsius to Fahrenheit?

Multiply by 9/5 (or 1.8), then add 32. For 25 °C: 25 × 1.8 + 32 = 77 °F.

Is there a quick mental shortcut?

For weather, double the Celsius value and add 30. At 20 °C that gives 70 °F against the exact 68 °F. The shortcut drifts at the extremes: at 40 °C it gives 110 °F instead of 104 °F, so use the exact formula for cooking or medical readings.

What is 350 °F in Celsius?

176.67 °C. An oven dial in Celsius rarely has that exact mark; 175 °C or 180 °C is close enough for most baking.

What is 0 kelvin in Fahrenheit and Celsius?

0 K, absolute zero, equals −273.15 °C and −459.67 °F. Nothing can be colder, so the converter shows an error for lower values.

Why is there no degree sign before K?

Because the kelvin is an SI base unit in its own right, not a degree of a scale. You write 300 K and say three hundred kelvin.

Sources

Conversions are exact and rounded for display. For food safety, use a food thermometer; for health questions about a temperature reading, ask a health professional.