Celsius to Fahrenheit Converter

1. Type the temperature in degrees Celsius. The answer updates as you type. Negative values and decimals both work.
2. Pick the decimal places. Zero or one is enough for weather and ovens. Two suits a thermometer reading such as 37.5.
3. Read the Fahrenheit result and the coloured band under it. Paste a list into the bulk box to convert a forecast or a recipe in one go.

In this guide, deg C means degrees Celsius and deg F means degrees Fahrenheit. The tool itself shows the degree sign.

A Celsius to Fahrenheit conversion restates a temperature from the metric Celsius scale on the Fahrenheit scale used in the United States. The temperature itself does not change. Only the number and the unit change.

The two scales disagree in two ways. First, their zero points differ. Water freezes at 0 deg C but at 32 deg F. Second, their degrees differ in size. NIST states that an interval of one Celsius degree equals an interval of 1.8 Fahrenheit degrees. That is why the ice-to-boiling span is 100 degrees on one scale and 180 on the other, from 32 to 212 deg F.

People need this conversion in three everyday places. A traveller or reader sees a Celsius forecast and wants the Fahrenheit feel. A cook follows a metric recipe on an oven marked in Fahrenheit. A parent reads a Celsius thermometer and wants the familiar Fahrenheit number. The same formula serves all three.

This page does not adjust for wind, humidity or oven type. It converts the reading you give it and nothing else.

The formula stretches each Celsius degree to 1.8 Fahrenheit degrees, then shifts the result up by 32 to match the Fahrenheit freezing point.

1. Multiply the Celsius value by 1.8. Example: 25 x 1.8 = 45.
2. Add 32. Example: 45 + 32 = 77 deg F.
3. Check by going back: (77 - 32) / 1.8 = 25 deg C.

The order matters. Multiply first, then add. NIST SP 811 writes the reverse relation as t/deg C = (t/deg F - 32)/1.8, and the formula above is that same line solved for Fahrenheit. Both 1.8 and 32 are exact, so nothing is rounded until you choose the decimal places.

For the story behind the two scales and more ways to remember the rule, read our guide to the Celsius to Fahrenheit formula and quick tricks.

Weather: a 28 deg C afternoon. 28 x 1.8 = 50.4, and 50.4 + 32 = 82.4 deg F. That is a warm day. A forecast low of -5 deg C is -9 + 32 = 23 deg F, well below freezing.

Oven: a recipe that says 180 deg C. 180 x 1.8 = 324, and 324 + 32 = 356 deg F. US recipes usually work in steps of 25 deg F, so cooks set 350. NIST lists 180 deg C and 350 deg F as approximate equals for a moderate oven. A 200 deg C recipe is exactly 392 deg F and is set as 400.

Body: a thermometer reading of 37 deg C. 37 x 1.8 = 66.6, and 66.6 + 32 = 98.6 deg F. MedlinePlus gives 98.6 deg F (37 deg C) as the generally accepted average, and notes that a reading over 100.4 deg F (38 deg C) most often means a fever. A reading of 38.5 deg C is 101.3 deg F.

A special case: -40. -40 x 1.8 = -72, and -72 + 32 = -40 deg F. This is the only temperature where both scales show the same number.

Planning a winter trip? Pair the converted reading with the wind chill calculator, because moving air makes cold feel colder than the thermometer shows.

The popular shortcut is "double it and add 30". It is quick, but it is only close for mild weather. The error is 0.2 x deg C - 2, in Fahrenheit degrees.

So the shortcut stays within 2 deg F from 0 to 20 deg C. It fails for body temperature, where it turns a normal 37 deg C into 104 deg F. It also fails for ovens.

An Exact Method You Can Do in Your Head

Double the Celsius value, take away one tenth of that, then add 32. For 25 deg C: double is 50, minus 5 is 45, plus 32 is 77 deg F. This is not an estimate. Doubling and removing a tenth is the same as multiplying by 1.8.

The formula is fixed, but four things decide whether the number you get is the number you need.

A Reading or a Change

A temperature such as 15 deg C needs the full formula and becomes 59 deg F. A change such as "5 deg C warmer tomorrow" needs only the 1.8 factor and becomes 9 deg F warmer. Adding 32 to a change gives 41, which is wrong.

The Precision of the Reading

Each 0.1 deg C step moves the answer by 0.18 deg F. A weather report in whole degrees Celsius cannot support a Fahrenheit answer with two decimals. Round the result to match the input.

Rounding for the Device

The exact answer is often not a setting you can dial. An oven at 220 deg C is exactly 428 deg F, yet the dial offers 425. The rounded figure is a kitchen convention, not a different formula.

The Scale of the Input

A value copied from a science source is sometimes in kelvin. Typing 300 K as 300 deg C turns a 26.85 deg C room into a 572 deg F oven. Check the unit symbol, then use the "Convert from" box.

Celsius and Fahrenheit measure the same thing with different anchor numbers and different degree sizes.

NIST records that Daniel Fahrenheit unveiled his scale in 1724, and that it was the main standard in English-speaking countries until the 1960s. The United States still uses it for weather, cooking and home thermostats. For readings that start in Fahrenheit, the mirror page has its own examples.

Reading a Foreign Forecast

Most countries publish weather in Celsius. NIST offers a simple memory aid: 30 is hot, 20 is nice, 10 is cold and 0 is ice. In Fahrenheit those are 86, 68, 50 and 32.

Cooking from a Metric Recipe

Recipes written outside the United States usually give oven heat in Celsius. Convert, then round to the nearest 25 deg F mark on a US oven. Our oven temperature conversion guide adds gas marks to the picture.

Checking a Thermometer Reading

Many digital thermometers default to Celsius. A reading of 36.1 deg C is 96.98 deg F and 37.2 deg C is 98.96 deg F, the ends of the normal range that MedlinePlus quotes as 97 to 99 deg F. For a tool built around this single use, see the body temperature converter. Neither page can tell you what a reading means for your health.

Setting Equipment

Some imported appliances and hobby devices list Celsius only. Convert once and write the Fahrenheit value on the device.

Exact values from deg F = deg C x 1.8 + 32.

Weather and Everyday Range

Oven Range

Every 5 deg C step adds exactly 9 deg F, so you can fill any gap by counting. The dial column rounds to the nearest 25 deg F, in line with the approximate oven table published by NIST.

1. Adding 32 Before Multiplying

(25 + 32) x 1.8 gives 102.6. The correct answer is 77. Multiply first.

2. Using 5/9 in Place of 9/5

The fraction 5/9 belongs to the reverse direction. 25 x 5/9 + 32 gives 45.89, which is far too low.

3. Forgetting the 32

25 x 1.8 is 45. That is the size of the rise above freezing, not the Fahrenheit reading.

4. Adding 32 to a Temperature Change

A fever that rises by 1.5 deg C has risen by 2.7 deg F, not 34.7.

5. Trusting the Shortcut at High Values

"Double and add 30" turns 180 deg C into 390 deg F. The true value is 356. That gap is enough to burn a cake.

6. Dropping the Minus Sign

-10 deg C is 14 deg F, while 10 deg C is 50 deg F. A lost sign shifts the answer by 36 deg F.

The conversion is exact, because 9/5 and 32 are fixed by definition. Only the display is rounded, to the decimals you pick.

20 deg C is 68 deg F. Multiply 20 by 1.8 to get 36, then add 32. NIST lists 20 deg C as a typical room temperature.

180 deg C is exactly 356 deg F. US ovens are set to 350 deg F for such recipes, because US recipes work in 25-degree steps.

37 deg C equals 98.6 deg F, which MedlinePlus gives as the generally accepted average. Normal readings vary by person, age, activity and time of day.

MedlinePlus states that a temperature over 38 deg C, which is 100.4 deg F, most often means a fever. This page converts the number only. Ask a clinician about symptoms.

There are 180 Fahrenheit degrees between freezing and boiling water, and 100 Celsius degrees. 180 divided by 100 is 9/5, or 1.8.

Water freezes at 0 on the Celsius scale and at 32 on the Fahrenheit scale. Adding 32 lines up the two starting points.

They are equal at -40. Below that point the Fahrenheit number is the lower of the two, and above it the Fahrenheit number is the higher.

Yes. 30 deg C is 86 deg F, a hot summer day in most climates. The NIST memory aid says 30 is hot, 20 is nice, 10 is cold and 0 is ice.

Type =A2*1.8+32 in a cell, with the Celsius value in A2. Fill the formula down the column to convert a whole list.

Use the same formula and keep the sign. For -15 deg C: -15 x 1.8 = -27, and -27 + 32 = 5 deg F.

No. The math runs in your browser. Saved results stay in your own browser storage until you clear them.

• Temperature conversion relations for degree Celsius, degree Fahrenheit and kelvin (NIST SP 811, Appendix B.9).
• Exact temperature conversion table, touchstone temperatures and oven equivalences (NIST Office of Weights and Measures).
• History of the Fahrenheit and Celsius scales (NIST, Kelvin: History).
• Body temperature norms in Fahrenheit and Celsius (MedlinePlus, US National Library of Medicine).