Fahrenheit to Celsius Converter

How Fahrenheit to Celsius Conversion Works

A Fahrenheit-to-Celsius conversion translates a temperature from the US customary scale to the metric standard used by the rest of the world. The formula is C = (F - 32) x 5/9, which reverses the Celsius-to-Fahrenheit calculation by first removing the 32-degree offset and then scaling down by the ratio of degree sizes.

The Celsius scale is the international standard for temperature measurement, recognized by the International Bureau of Weights and Measures (BIPM) and used by scientists, governments, and businesses in 195+ countries. In the Celsius scale, water freezes at 0 degrees and boils at 100 degrees under standard atmospheric conditions.

According to the NIST, the US has been slowly adopting Celsius in scientific and medical contexts. Drug storage temperatures, laboratory standards, and weather data for international exchange are all recorded in Celsius. However, daily weather forecasts, cooking, and home thermostats in the US still use Fahrenheit. Use our Temperature Converter to also convert between Kelvin and Rankine.

The Fahrenheit to Celsius Formula

The exact formula to convert Fahrenheit to Celsius is:

°C = (°F - 32) x 5/9

Or equivalently: °C = (°F - 32) / 1.8

Subtracting 32 aligns the zero points (32°F = 0°C). Multiplying by 5/9 converts from the smaller Fahrenheit degrees to the larger Celsius degrees, since one Celsius degree equals 1.8 Fahrenheit degrees.

Worked example: Convert 72°F (a typical US room temperature) to Celsius. Using the formula: (72 - 32) x 5/9 = 40 x 0.5556 = 22.22°C. For the reverse, see our Celsius to Fahrenheit Converter.

Key Terms You Should Know

• Fahrenheit (°F) -- A temperature scale created by Daniel Gabriel Fahrenheit in 1724. Water freezes at 32°F and boils at 212°F. The 180-degree span between these points compares to 100 degrees in Celsius.
• Celsius (°C) -- The international standard temperature scale, part of the SI system. Water freezes at 0°C and boils at 100°C. Used worldwide for weather, science, and commerce.
• Kelvin (K) -- The SI base unit of thermodynamic temperature. One Kelvin equals one Celsius degree in size, but the scale starts at absolute zero. To convert: K = °C + 273.15.
• Rankine (°R) -- An absolute temperature scale using Fahrenheit-sized degrees. Used primarily in some US engineering contexts. °R = °F + 459.67.
• Thermodynamic Temperature -- Temperature measured from absolute zero, used in physics and engineering. The Kelvin and Rankine scales are thermodynamic; Celsius and Fahrenheit are not.

Common Fahrenheit to Celsius Conversion Table

This table shows commonly referenced Fahrenheit temperatures and their Celsius equivalents, covering weather, body temperature, cooking, and science.

Practical Examples

International travel weather: Before traveling to Europe, you check your destination's weather and see highs of 28°C. To understand in Fahrenheit terms: (28 x 1.8) + 32 = 82.4°F -- warm and pleasant. Conversely, if a US forecast says 95°F, that is (95 - 32) / 1.8 = 35°C, which is very hot. According to the World Meteorological Organization, the highest temperature ever recorded was 56.7°C (134°F) in Death Valley, California in 1913.

Cooking with US recipes abroad: An American recipe calls for baking at 375°F. Converting: (375 - 32) / 1.8 = 190.6°C. Set your European oven to 190°C. For deep frying at 350°F, that is 176.7°C (use 175°C). Candy-making temperatures are critical: soft ball stage is 235-240°F (113-116°C) and hard crack is 300-310°F (149-154°C). See our Cooking Converter for more kitchen conversions.

HVAC and home comfort: US thermostats are set in Fahrenheit -- a typical setting of 68°F equals 20°C, and 72°F equals 22.2°C. The US Department of Energy recommends setting thermostats to 68°F (20°C) in winter for energy savings. In summer, 78°F (25.6°C) is recommended when home. Understanding both scales helps when purchasing international HVAC equipment or following energy guides. Check costs with our Energy Converter.

Tips for Accurate F to C Conversions

• Use the "subtract 30, divide by 2" shortcut: For rough mental math, subtract 30 and halve the result. Example: 90°F: (90-30)/2 = 30°C (exact: 32.2°C). This works best in the 40-100°F range.
• Remember that Fahrenheit degrees are smaller: A 10°F change equals only a 5.56°C change. This is why Fahrenheit appears to offer more "resolution" -- the numbers change more for the same actual temperature shift.
• Know the oven quick-reference: 300°F = 150°C, 350°F = 180°C, 400°F = 200°C, 450°F = 230°C. These rounded equivalents work for all standard baking.
• For body temperature, memorize the thresholds: Normal: 98.6°F = 37°C. Fever: 100.4°F = 38°C. High fever: 103°F = 39.4°C. Hypothermia: below 95°F = 35°C.
• For weather, use decade anchors: 50°F = 10°C, 60°F = 15.6°C, 70°F = 21.1°C, 80°F = 26.7°C, 90°F = 32.2°C, 100°F = 37.8°C. Interpolate between these for quick estimates.

Temperature Scales in Science and Industry

In scientific research, temperature is predominantly expressed in Celsius or Kelvin. The BIPM defines the Kelvin as the SI base unit of thermodynamic temperature, fixed by setting the Boltzmann constant to exactly 1.380649 x 10^-23 J/K as of the 2019 SI redefinition. Since Kelvin and Celsius use the same degree size (differing only by the 273.15-degree offset), scientific conversions between them are straightforward.

In US engineering, some fields still use the Rankine scale (°R = °F + 459.67), which is an absolute scale with Fahrenheit-sized degrees. This appears in thermodynamic calculations, particularly in the US HVAC and petroleum industries. However, global engineering practice has largely shifted to Kelvin and Celsius, and US-trained engineers increasingly work with both systems.