Fahrenheit to Celsius Converter

Fahrenheit to Celsius conversion table

How to convert fahrenheit to celsius

°C = (°F − 32) × 5/9. For example, -10 °F = -23.333333 °C. Type a value in either box above: the other one updates instantly, both ways.

What is a degree Fahrenheit?

The Fahrenheit scale (°F) sets water's freezing point at 32 °F and its boiling point at 212 °F; it is used mainly in the United States.

What is a degree Celsius?

The Celsius scale (°C) sets water's freezing point at 0 °C and its boiling point at 100 °C at sea level; it is used in most countries.

Which number belongs in the fahrenheit input?

Enter the numerical quantity measured in fahrenheit, leaving the °F symbol in the label rather than inside the input. The second field represents celsius and uses °C. Both fields can be edited, but each has its own direction of conversion. Decide which quantity you know before typing. Decimal values are allowed; a mixed fraction or a number followed by descriptive text is not a numeric entry. Use the decimal separator accepted by your browser's number field and avoid pasted thousands separators when a value could be interpreted ambiguously.

How is the conversion calculated?

Use the complete expression °C = (°F − 32) × 5/9. The implementation first expresses the source reading in Celsius, then converts that Celsius value to the destination scale. Parentheses establish which subtraction happens before multiplication. Keep the offset and the scale together: multiplying the source reading by a ratio alone does not convert an absolute temperature. A spreadsheet should preserve the same order of operations even if it uses different cell names.

How can I check the intermediate calculation?

To inspect the scale separately from the zero point, compare 10 °F and 20 °F. Their converted readings are -12.2222222222222 °C and -6.66666666666667 °C. Subtracting the two destination readings gives 5.55555555555555 destination degrees for a ten-degree source change. The zero-point offset cancels in that subtraction. Do not enter a temperature increase into the absolute-reading formula and interpret the offset as part of the increase. A temperature reading and a change in temperature have related but distinct conversion rules.

Can I combine values before converting?

Temperature readings should not normally be added as if they were amounts of material. Adding two Celsius readings and converting that sum counts the zero-point offset differently from adding two Fahrenheit readings. An arithmetic average is consistent across these affine scales when the same weights sum to one, because the offset is then counted once. That mathematical property does not decide whether an average describes your physical system: unequal masses or different heat capacities need their own model. Use this page to change the scale of a known reading and keep any physical mixing calculation separate from the scale conversion.

Worked values and a direction check

A reading of 37 °F becomes 2.77777777777778 °C. A zero reading becomes -17.7777777777778 °C, while 100 °F becomes 37.7777777777778 °C. Compare these separate reference points with the table above. They show both the shift in zero point and the change in scale. Doubling a source reading does not generally double its destination reading because the offset remains.

What conventions apply to this family?

Temperature scales have different zero points. Celsius and Fahrenheit also have different degree sizes, while Celsius and Kelvin have the same degree size and a 273.15 offset. The formula here converts a temperature reading, not a temperature difference. For example a ten-degree Celsius increase corresponds to an eighteen-degree Fahrenheit increase; adding thirty-two to that increase would be incorrect. Negative Celsius and Fahrenheit readings can be ordinary temperatures, but a negative Kelvin reading is outside the physical scale. The arithmetic can still return a number for such an input, so treat the formula as a scale conversion rather than a plausibility check or a thermometer calibration.

How much precision should I keep?

The displayed answer is a readable representation of a floating-point calculation. Very large or very small results may appear in scientific notation: the exponent indicates how many places to move the decimal point, rather than another unit. A short displayed factor can hide digits used internally. Use the full conversion expression for a spreadsheet instead of repeatedly multiplying by a rounded answer copied from the table. Round once, at the end, to the resolution your measurement supports. Extra digits in a conversion cannot improve the precision of a ruler, sensor, product label or original estimate.

How can I check a value before reusing it?

Keep both the source quantity and its °F unit beside the answer in °C. Use the reverse field or the Swap link to check that converting back approaches the original number. Small differences after copying a rounded answer are expected; a large difference suggests a wrong direction, wrong family, or missing decimal place. Check the order of magnitude as well as the digits. Converting to a smaller unit usually produces a larger count for fixed-factor families, while temperature offsets need their own reference-point checks. An inverse check establishes consistency of the arithmetic, not accuracy of the original measurement.