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Temperature Converter — Celsius, Fahrenheit, Kelvin, Rankine

0 °C = 32 °F = 273.15 K = 491.67 °R. Convert Celsius, Fahrenheit, Kelvin & Rankine instantly — free, private, browser-based. Includes conversion formulas, step-by-step guides, and reference charts.

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Reviewed for mathematical accuracy and scientific correctness — Go-Tools Editorial Team · Mar 17, 2026

Quick Reference

What Is 0 °C in Fahrenheit?

0 °C = 32 °F (freezing point of water) 0 °C is the freezing point of water. Using the formula °F = °C × 9/5 + 32: 0 × 1.8 + 32 = 32 °F. This is one of the two key reference points between the scales.

What Is 100 °C in Fahrenheit?

100 °C = 212 °F (boiling point of water) 100 °C is the boiling point of water at standard pressure. Using the formula: 100 × 1.8 + 32 = 212 °F. The 180-degree span between 32 °F and 212 °F corresponds to the 100-degree span between 0 °C and 100 °C.

What Is Normal Body Temperature?

37 °C = 98.6 °F = 310.15 K Normal human body temperature is approximately 37 °C, which equals 98.6 °F or 310.15 K. Note that actual body temperature varies slightly by individual and time of day, typically ranging from 36.1 °C to 37.2 °C (97 °F to 99 °F).

What Is 72 °F in Celsius?

72 °F = 22.22 °C (room temperature) 72 °F is a common US room temperature setting. Using °C = (°F − 32) × 5/9: (72 − 32) × 5/9 = 22.22 °C. In most countries using Celsius, this falls in the comfortable 20–25 °C range.

What Is −40 °C in Fahrenheit?

−40 °C = −40 °F (the only equal point) −40 is the unique temperature where Celsius and Fahrenheit scales meet. You can verify: °F = −40 × 1.8 + 32 = −40. This crossover point is a popular science fact and useful for understanding the relationship between the two scales.

What Temperature Is 180 °C for Baking?

180 °C = 356 °F (common baking temp) Many European and international recipes call for 180 °C, which equals 356 °F. In practice, US ovens are typically set to 350 °F — the closest standard marking. This is the most common baking temperature for cakes, cookies, and breads.

Temperature Conversion Formulas

Complete reference of all temperature conversion formulas between Celsius, Fahrenheit, Kelvin, and Rankine with worked examples.

Celsius to Fahrenheit

°F = °C × 9/5 + 32

°F = °C × 1.8 + 32

25 °C →

  1. 25 × 1.8 = 45
  2. 45 + 32 = 77

= 77 °F

Fahrenheit to Celsius

°C = (°F − 32) × 5/9

°C = (°F − 32) / 1.8

72 °F →

  1. 72 − 32 = 40
  2. 40 × 5/9 = 22.22

= 22.22 °C

Celsius to Kelvin

K = °C + 273.15

20 °C →

  1. 20 + 273.15 = 293.15

= 293.15 K

Kelvin to Celsius

°C = K − 273.15

300 K →

  1. 300 − 273.15 = 26.85

= 26.85 °C

Fahrenheit to Kelvin

K = (°F − 32) × 5/9 + 273.15

212 °F →

  1. 212 − 32 = 180
  2. 180 × 5/9 = 100
  3. 100 + 273.15 = 373.15

= 373.15 K

Kelvin to Fahrenheit

°F = (K − 273.15) × 9/5 + 32

373.15 K →

  1. 373.15 − 273.15 = 100
  2. 100 × 1.8 = 180
  3. 180 + 32 = 212

= 212 °F

What Is a Temperature Converter?

A temperature converter is a tool that translates temperature measurements between different scales. The four major temperature scales are:

**Celsius (°C)** — used worldwide for everyday temperature measurement. Water freezes at 0 °C and boils at 100 °C at standard pressure. Developed by Anders Celsius in 1742.

**Fahrenheit (°F)** — used primarily in the United States for weather, cooking, and medical contexts. Water freezes at 32 °F and boils at 212 °F. Developed by Daniel Gabriel Fahrenheit in 1724.

**Kelvin (K)** — the SI unit of temperature, used in science and engineering. It starts at absolute zero (0 K = −273.15 °C), the lowest theoretically possible temperature. A change of 1 K equals a change of 1 °C.

**Rankine (°R)** — an absolute temperature scale based on Fahrenheit degrees. Used in some US engineering applications. 0 °R = absolute zero = −459.67 °F.

Unlike length or mass conversions that use simple multiplication factors, temperature conversions require formulas because the scales have different zero points and (in some cases) different degree sizes. All conversions in this tool use the exact mathematical formulas, running entirely in your browser with no server calls.

// Temperature conversion formulas:
// Celsius to Fahrenheit: °F = °C × 9/5 + 32
// Fahrenheit to Celsius: °C = (°F − 32) × 5/9
// Celsius to Kelvin:     K = °C + 273.15
// Kelvin to Celsius:     °C = K − 273.15

const celsiusToFahrenheit = (c) => c * 9/5 + 32;
const fahrenheitToCelsius = (f) => (f - 32) * 5/9;
const celsiusToKelvin = (c) => c + 273.15;
const kelvinToCelsius = (k) => k - 273.15;

console.log(celsiusToFahrenheit(100)); // 212
console.log(fahrenheitToCelsius(98.6)); // 37
console.log(celsiusToKelvin(0));        // 273.15

Key Features of This Temperature Converter

4 Temperature Scales

Convert between Celsius (°C), Fahrenheit (°F), Kelvin (K), and Rankine (°R) — covering everyday, scientific, and engineering needs.

Instant Real-Time Conversion

Results update as you type — no need to click a convert button. Change units and see the result immediately.

One-Click Swap

Reverse the conversion direction instantly with the swap button, without re-entering your value.

Exact Mathematical Formulas

Uses the exact temperature conversion formulas with double-precision arithmetic for maximum accuracy.

Negative & Extreme Values

Handles negative temperatures, absolute zero, and extreme values correctly — essential for scientific and engineering work.

100% Browser-Based & Private

All calculations happen locally in your browser. No server requests, no tracking, no data storage — your values never leave your device.

Temperature Conversion Examples

Boiling Point of Water — Celsius to Fahrenheit

100 °C
212 °F

Water boils at 100 °C (212 °F) at standard atmospheric pressure. The formula is °F = °C × 9/5 + 32, so 100 × 9/5 + 32 = 212.

Body Temperature — Fahrenheit to Celsius

98.6 °F
37 °C

Normal human body temperature is 98.6 °F, which equals exactly 37 °C. The formula is °C = (°F − 32) × 5/9.

Absolute Zero — Kelvin to Celsius

0 K
−273.15 °C

Absolute zero (0 K) is the lowest theoretically possible temperature, equal to −273.15 °C. At this point, all molecular motion ceases.

Room Temperature — Celsius to Kelvin

20 °C
293.15 K

A comfortable room temperature of 20 °C equals 293.15 K. The conversion is simple: K = °C + 273.15.

Freezing Point — Celsius to Rankine

0 °C
491.67 °R

The freezing point of water (0 °C) equals 491.67 °R. Rankine is the Fahrenheit-scale equivalent of Kelvin, used in some engineering applications.

How to Convert Common Temperature Units

Quick reference for the most popular temperature unit conversions between Celsius, Fahrenheit, and Kelvin.

How to Convert Celsius to Fahrenheit

Celsius (°C) → Fahrenheit (°F)

Multiply the Celsius value by 9/5 (or 1.8), then add 32. For example, 25 °C = 25 × 1.8 + 32 = 77 °F. This is the most commonly needed temperature conversion for everyday use.

25 °C → 77 °F

For a quick mental estimate, double the Celsius value and add 30. This gives 25 °C ≈ 80 °F (actual: 77 °F) — close enough for everyday use.

Try it above — enter your value and see the result instantly.

How to Convert Fahrenheit to Celsius

Fahrenheit (°F) → Celsius (°C)

Subtract 32 from the Fahrenheit value, then multiply by 5/9. For example, 72 °F = (72 − 32) × 5/9 = 22.22 °C. Essential when interpreting US weather forecasts or recipe temperatures.

72 °F → 22.22 °C

For a quick estimate, subtract 30 and divide by 2. This gives 72 °F ≈ 21 °C (actual: 22.2 °C) — good enough for weather context.

Try it above — enter your value and see the result instantly.

How to Convert Celsius to Kelvin

Celsius (°C) → Kelvin (K)

Simply add 273.15 to the Celsius value. For example, 20 °C = 20 + 273.15 = 293.15 K. This is the simplest temperature conversion — just an offset, no scaling required.

20 °C → 293.15 K

Remember that 0 °C = 273.15 K. For rough calculations in science, 273 K is often used as the approximate offset.

Try it above — enter your value and see the result instantly.

How to Convert Kelvin to Fahrenheit

Kelvin (K) → Fahrenheit (°F)

Subtract 273.15 to get Celsius, then multiply by 9/5 and add 32. Or use the direct formula: °F = (K − 273.15) × 9/5 + 32. For example, 373.15 K = 100 °C = 212 °F.

373.15 K → 212 °F

Convert to Celsius first (subtract 273.15), then to Fahrenheit — it is easier to keep track of two simple steps.

Try it above — enter your value and see the result instantly.

Temperature Conversion Charts

Pre-calculated reference tables for common temperature conversions. Bookmark this page for quick lookups — includes key temperature landmarks.

Celsius to Fahrenheit Chart

Celsius to Fahrenheit conversion table (−273.15 to 500 °C)
C F
-273.15 Absolute zero -459.67
-200 -328
-150 -238
-100 -148
-50 -58
-40 -40
-35 -31
-30 -22
-25 -13
-20 -4
-15 5
-10 14
-5 23
0 Freezing point 32
5 41
10 50
15 59
20 68
25 77
30 86
35 95
37 Body temp 98.6
40 104
45 113
50 122
55 131
60 140
65 149
70 158
75 167
80 176
85 185
90 194
95 203
100 Boiling point 212
150 302
200 392
250 482
300 572
350 High baking 662
400 752
450 842
500 932

Fahrenheit to Celsius Chart

Fahrenheit to Celsius conversion table (−459.67 to 932 °F)
F C
-459.67 Absolute zero -273.15
-400 -240
-300 -184.444444444
-200 -128.888888889
-100 -73.3333333333
-40 -40
-30 -34.4444444444
-20 -28.8888888889
-10 -23.3333333333
0 -17.7777777778
10 -12.2222222222
20 -6.66666666667
30 -1.11111111111
40 4.44444444444
50 10
60 15.5555555556
70 21.1111111111
80 26.6666666667
90 32.2222222222
100 37.7777777778
110 43.3333333333
120 48.8888888889
130 54.4444444444
140 60
150 65.5555555556
160 71.1111111111
170 76.6666666667
180 82.2222222222
190 87.7777777778
200 93.3333333333
210 98.8888888889
300 148.888888889
400 204.444444444
500 260
600 315.555555556
700 371.111111111
800 426.666666667
900 482.222222222

Celsius to Kelvin Chart

Celsius to Kelvin conversion table (−273.15 to 500 °C)
C K
-273.15 Absolute zero 0
-200 73.15
-150 123.15
-100 173.15
-50 223.15
-50 223.15
-40 233.15
-30 243.15
-20 253.15
-10 263.15
0 Freezing point 273.15
10 283.15
20 293.15
30 303.15
40 313.15
50 323.15
60 333.15
70 343.15
80 353.15
90 363.15
100 Boiling point 373.15
150 423.15
200 473.15
250 523.15
300 573.15
350 623.15
400 673.15
450 723.15
500 773.15

Fahrenheit to Kelvin Chart

Fahrenheit to Kelvin conversion table (−459.67 to 932 °F)
F K
-459.67 Absolute zero -5.684342e-14
-400 33.15
-300 88.7055555556
-200 144.261111111
-100 199.816666667
-40 233.15
-30 238.705555556
-20 244.261111111
-10 249.816666667
0 255.372222222
10 260.927777778
20 266.483333333
30 272.038888889
40 277.594444444
50 283.15
60 288.705555556
70 294.261111111
80 299.816666667
90 305.372222222
100 310.927777778
110 316.483333333
120 322.038888889
130 327.594444444
140 333.15
150 338.705555556
160 344.261111111
170 349.816666667
180 355.372222222
190 360.927777778
200 366.483333333
210 372.038888889
300 422.038888889
400 477.594444444
500 533.15
600 588.705555556
700 644.261111111
800 699.816666667
900 755.372222222

Kelvin to Celsius Chart

Kelvin to Celsius conversion table (0 to 773.15 K)
K C
0 Absolute zero -273.15
50 -223.15
100 -173.15
150 -123.15
200 -73.15
250 -23.15
273.15 Freezing point 0
280 6.85
290 16.85
300 26.85
310 36.85
320 46.85
330 56.85
340 66.85
350 76.85
360 86.85
370 96.85
373.15 Boiling point 100
400 126.85
450 176.85
500 226.85
550 276.85
600 326.85
650 376.85
700 426.85
750 476.85

How to Use the Temperature Converter

  1. 1

    Enter a Temperature

    Type or paste a numeric value into the input field. The tool accepts integers, decimals, and negative numbers.

  2. 2

    Select the Source Unit

    Choose the unit you are converting from using the 'From' dropdown: Celsius (°C), Fahrenheit (°F), Kelvin (K), or Rankine (°R).

  3. 3

    Select the Target Unit

    Choose the unit you want to convert to using the 'To' dropdown. The result updates instantly as you change either unit.

  4. 4

    Copy or Swap

    Click the copy button to copy the result to your clipboard. Use the swap button to reverse the conversion direction instantly.

Use Cases for Temperature Conversion

Cooking & Recipes
Convert oven temperatures between Celsius and Fahrenheit when following international recipes (e.g., 180 °C = 356 °F for baking).
Weather & Travel
Understand weather forecasts in unfamiliar temperature scales when traveling between countries that use Celsius and Fahrenheit.
Science & Research
Convert between Kelvin and Celsius for laboratory experiments, chemical reactions, and physics calculations.
Engineering & Thermodynamics
Use Kelvin and Rankine for thermodynamic calculations, heat transfer analysis, and process engineering.
Medical & Healthcare
Convert body temperature readings between Celsius and Fahrenheit for medical records and international communication.
Programming & Data Processing
Convert temperature data from APIs, sensors, or datasets that may use different temperature scales.

Technical Details

Exact Conversion Formulas
°F = °C × 9/5 + 32, K = °C + 273.15, °R = °F + 459.67. These are mathematically exact relationships with no approximation involved.
Double-Precision Arithmetic
Uses IEEE 754 double-precision floating-point numbers, providing at least 15 significant digits of precision for all conversions.
Client-Side Processing
All conversion logic runs in JavaScript within your browser. Zero network calls are made — the tool works fully offline once loaded.

Best Practices for Temperature Conversion

Use Kelvin for Scientific Work
Kelvin is the SI unit and starts at absolute zero, making it the natural choice for thermodynamic equations and scientific calculations.
Remember Key Reference Points
Memorize a few anchor points: 0 °C = 32 °F (freezing), 100 °C = 212 °F (boiling), 37 °C = 98.6 °F (body temp), −40 °C = −40 °F (equal point).
Check Context Before Converting
Verify which temperature scale your data uses before converting. Misinterpreting Celsius as Fahrenheit (or vice versa) can lead to dangerous errors in cooking, medical, and engineering contexts.

Temperature Conversion FAQ

What is the formula to convert Celsius to Fahrenheit?
The formula is °F = °C × 9/5 + 32. To convert Celsius to Fahrenheit, multiply the Celsius value by 9/5 (or 1.8), then add 32. For example, 25 °C = 25 × 1.8 + 32 = 77 °F. To convert back, use °C = (°F − 32) × 5/9. Common reference points: 0 °C = 32 °F (freezing), 100 °C = 212 °F (boiling), 37 °C = 98.6 °F (body temperature).
What is the difference between Celsius and Kelvin?
Celsius and Kelvin use the same degree size — a 1-degree change in Celsius equals a 1-degree change in Kelvin. The only difference is the zero point: 0 K (absolute zero) equals −273.15 °C. To convert, use K = °C + 273.15 or °C = K − 273.15. Kelvin is the SI unit of temperature and is used in scientific contexts because it starts at absolute zero, making it ideal for thermodynamic calculations.
What is absolute zero?
Absolute zero is the lowest possible temperature, defined as 0 K (Kelvin), which equals −273.15 °C or −459.67 °F. At absolute zero, atoms reach their lowest energy state and thermal motion effectively ceases. While absolute zero cannot be physically achieved, scientists have cooled matter to within billionths of a degree above it. It serves as the foundation for the Kelvin scale and is essential in thermodynamics, cryogenics, and quantum physics.
What is the Rankine scale and when is it used?
The Rankine scale (°R) is an absolute temperature scale based on the Fahrenheit degree. Just as Kelvin uses Celsius-sized degrees starting from absolute zero, Rankine uses Fahrenheit-sized degrees starting from absolute zero (0 °R = −459.67 °F). It is primarily used in certain engineering fields in the United States, particularly in thermodynamic calculations involving the Fahrenheit system. To convert: °R = °F + 459.67 or °R = K × 9/5.
At what temperature are Celsius and Fahrenheit equal?
Celsius and Fahrenheit are equal at −40 degrees. You can prove this algebraically: set °C = °F in the formula °F = °C × 9/5 + 32, which gives °C = °C × 9/5 + 32, solving to °C = −40. This is the only point where the two scales intersect, and it serves as a useful memory aid for understanding the relationship between the scales.
Why does the United States use Fahrenheit instead of Celsius?
The United States inherited the Fahrenheit scale from the British system before the metric system gained global adoption. While most countries switched to Celsius during metrication in the 1960s–1970s, the US never completed the transition. Fahrenheit remains in everyday use for weather, cooking, and medical contexts. However, US scientists, engineers, and the military typically use Celsius or Kelvin. The Fahrenheit scale offers slightly finer granularity for ambient temperatures (180 degrees between freezing and boiling vs. 100 in Celsius).
How accurate is this temperature converter?
This converter uses the exact mathematical formulas for temperature conversion with IEEE 754 double-precision floating-point arithmetic, providing at least 15 significant digits of precision. The conversion formulas are exact — there are no approximations in the mathematical relationships between Celsius, Fahrenheit, Kelvin, and Rankine. The only limitation is inherent floating-point rounding at extreme precision levels.
Is my data safe when using this temperature converter?
Yes, completely. All conversions are performed locally in your browser using JavaScript. No data is sent to any server — there are no network requests, no cookies, and no analytics on your input. The conversion logic runs entirely on your device, meaning your values never leave your browser. You can verify this by disconnecting from the internet and using the tool — it works fully offline once the page has loaded.
What is the easiest way to convert Celsius to Fahrenheit in your head?
The simplest mental trick for Celsius to Fahrenheit: double the Celsius value and add 30. For example, 20 °C → 20 × 2 + 30 = 70 °F (actual: 68 °F). For Fahrenheit to Celsius: subtract 30 and divide by 2. These shortcuts are accurate within ±2–3 degrees for everyday temperatures (0–40 °C), which is close enough for weather and travel.
What temperature is 350 °F in Celsius?
350 °F equals approximately 176.67 °C. In practice, this is rounded to 175 °C or 180 °C depending on the recipe. This is the most common oven temperature in American baking, used for cookies, cakes, casseroles, and roasted vegetables. European recipes typically list this as 180 °C.
Why do scientists use Kelvin instead of Celsius?
Scientists prefer Kelvin because it is an absolute scale starting at absolute zero (0 K), where all thermal motion ceases. This makes thermodynamic equations simpler — you can directly multiply, divide, and compare temperatures without negative numbers or offset adjustments. The Kelvin is also the SI base unit of temperature, ensuring consistency across international scientific communication.
Can temperatures go below absolute zero?
In classical thermodynamics, absolute zero (0 K) is the lower limit. However, in quantum physics, researchers have created systems with 'negative absolute temperatures' — but this does not mean colder than absolute zero. Negative temperatures describe inverted energy distributions where most particles occupy high-energy states. These systems are actually hotter than any positive temperature, as energy flows from them to any positive-temperature system.

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