Fahrenheit to Celsius Converter

Fahrenheit to Celsius formula

The subtraction adjusts for the different zero points of the two scales. Multiplication by five-ninths adjusts for the different size of one degree on each scale.

Formula symbols

• °F represents degrees Fahrenheit.
• °C represents degrees Celsius.
• 32 accounts for the offset between the scales.
• 5/9 adjusts the size of the degree interval.

How to convert Fahrenheit to Celsius

1. Write down the Fahrenheit temperature. Keep any negative sign or decimal portion.
2. Subtract 32. Complete this subtraction before multiplying.
3. Multiply the result by 5.
4. Divide by 9. This is equivalent to multiplying by five-ninths.
5. Round only when needed. Keep enough precision for the intended use.

Example: convert 68°F to Celsius

Example: convert 95°F to Celsius

Example: convert 50°F to Celsius

How to convert decimal Fahrenheit values

Decimal temperatures use the same formula. Keep the decimal portion through the complete calculation.

Example: convert 98.6°F

Example: convert 72.5°F

How to convert negative Fahrenheit temperatures

Keep the negative sign and perform the subtraction carefully. Subtracting 32 from a negative number makes the intermediate value more negative.

Example: convert -4°F

Example: convert -40°F

Minus 40 is the point where the two temperature scales show the same numerical value.

Fahrenheit to Celsius conversion table

Why Fahrenheit and Celsius use different formulas

Fahrenheit and Celsius differ in both their zero points and their degree intervals. Water freezes at 32°F and 0°C under standard reference conditions. Water boils at 212°F and 100°C under standard reference conditions.

The distance between freezing and boiling is:

• 180 Fahrenheit degrees;
• 100 Celsius degrees.

The ratio between these intervals is 100 divided by 180, which simplifies to five-ninths. This explains the multiplication portion of the conversion formula.

Important reference temperatures

Common uses for Fahrenheit to Celsius conversion

Weather forecasts

Weather services may use Fahrenheit in the United States and Celsius in most other countries. Conversion helps compare outdoor conditions and travel forecasts.

Cooking and baking

Recipes and ovens may use different temperature scales. Oven settings are often rounded to convenient values, so exact conversion and practical settings may differ slightly.

Body-temperature readings

Thermometers and records may use either scale. Keep the original reading and use appropriate precision when converting.

Refrigerators and freezers

Appliance settings, manuals, and food-storage guidance may present temperatures in Fahrenheit or Celsius.

Water and pool temperatures

Pool, bath, aquarium, and general water measurements may need to be compared across both scales.

How to estimate Fahrenheit to Celsius mentally

A quick estimate is:

Example: estimate 70°F

The exact result is approximately 21.11°C. The mental method is convenient for weather and casual comparisons, but it is not exact.

Example: estimate 90°F

The exact result is approximately 32.22°C.

Exact conversion and rounding

Many Fahrenheit values produce repeating or long decimal Celsius results. The useful rounding level depends on the application.

• Whole degrees may be sufficient for general weather discussion.
• One decimal place may suit many thermostat readings.
• Two decimal places may be useful for detailed comparisons.
• Technical or scientific work may require greater precision.

Avoid displaying more precision than the original temperature measurement supports.

Common conversion mistakes

Multiplying before subtracting 32

Parentheses matter. Subtract 32 first, then multiply by five-ninths.

Using the reverse formula

Multiplying by nine-fifths and adding 32 converts Celsius to Fahrenheit, not Fahrenheit to Celsius.

Dividing by 5/9

Multiply by five-ninths. Dividing by five-ninths reverses the scale adjustment.

Losing a negative sign

Temperatures below 32°F convert to values below 0°C. Keep all signs through each step.

Treating the mental estimate as exact

Subtracting 30 and dividing by 2 provides only an approximation.

Reverse the conversion

To convert Celsius back to Fahrenheit, multiply by nine-fifths and add 32.

Convert Celsius to Fahrenheit

Fahrenheit to Celsius supporting guides

Use these focused guides for weather, body temperature, ovens, appliances, water, negative values, decimals, reference points, mental estimation, and charts.

Frequently asked questions