How is Celsius to Fahrenheit calculated?

F = (C × 9/5) + 32. So 0°C = 32°F (water freezes), 100°C = 212°F (water boils), 20°C = 68°F (room temperature). The 9/5 ratio comes from the fact that the F scale spans 180 degrees between water's freezing and boiling, while C spans 100.

What's Kelvin and why use it?

Kelvin (K) is the SI unit of temperature, starting at absolute zero (-273.15°C). Used in scientific contexts where negative temperatures don't make physical sense. 0 K = -273.15°C = -459.67°F. Each K is the same size as 1°C, just shifted: K = C + 273.15.

What's absolute zero?

0 Kelvin = -273.15°C = -459.67°F. The lowest theoretically possible temperature where all atomic motion stops. Has never been achieved; physics laws prevent reaching it (only approaching). Essential reference point in physics, cryogenics, and statistical mechanics.

Why does the US use Fahrenheit?

Historical reasons. Fahrenheit was developed in early 1700s; Celsius later. The US adopted Fahrenheit early and has stuck with it. Most other countries use Celsius (and SI units generally). Scientific and medical contexts in US sometimes use Celsius even though general public uses Fahrenheit.

Where is Rankine used?

Rankine (°R) is mostly used in US engineering for thermodynamics, especially aerospace and energy industries. Equal to Kelvin but in Fahrenheit-sized degrees: 0°R = absolute zero, 459.67°R = 0°F. Conversion: R = F + 459.67. Less common than other scales.

What about wind chill and heat index?

Those are different concepts — they're 'apparent' temperatures combining actual temperature with wind/humidity. The calculator handles raw temperature conversions. For wind chill or heat index, use specialized weather calculators that incorporate the additional factors.

Is the conversion exact?

Yes. The conversion formulas use exact relationships defined by international standards. Any temperature converts to other scales without rounding error in the formula. Display precision (decimal places) is up to you — for everyday use, 1 decimal is plenty.

Temperature Converter

Convert between Celsius, Fahrenheit, and Kelvin online. Free temperature converter with instant results and conversion formulas.

Calculators Unit Converters

Instant results

Enter value to convert

Conversions

Celsius

100°C

Fahrenheit

212°F

Kelvin

373.15K

How to Use Temperature Converter

Enter temperature

Type the value and select source scale (Celsius, Fahrenheit, Kelvin, Rankine).

Choose target scale

Select destination scale. Conversion is instant using exact formulas (no rounding).

Verify special points

Check known reference points: 0°C = 32°F, 100°C = 212°F, 0 K = -273.15°C. Validates your conversion.

Use for context

Apply to weather (C/F), cooking (recipes vary by country), science (Kelvin), and engineering (Rankine in some US fields).

When to Use Temperature Converter

Cooking and baking

International recipes use different temperature scales: US oven temperatures in Fahrenheit (350°F, 425°F); European in Celsius (180°C, 220°C). Convert when following recipes from different cuisines or using imported cookbooks.

Weather across regions

When traveling or communicating internationally, weather forecasts may use unfamiliar scales. 30°C (Australia summer) = 86°F. -10°C (Northern winter) = 14°F. Quick conversion helps you understand conditions in unfamiliar units.

Scientific work

Chemistry/physics use Kelvin for absolute temperature work. Engineering uses Fahrenheit (US) or Celsius. Convert as needed for cross-disciplinary collaboration or international research papers.

Health and medical contexts

Body temperature: 98.6°F = 37°C (normal). Fever threshold: 100.4°F = 38°C. Medical decisions often depend on temperature; conversion ensures correct interpretation across thermometer types and international patient records.

Temperature Converter Examples

Common temperatures

Input

100°F

Output

37.78°C = 310.93 K = 559.67°R

100°F is just over body temperature. The conversion shows all major scales: Celsius for international medical contexts, Kelvin for scientific work, Rankine for US engineering thermodynamics.

Cooking conversion

Input

180°C

Output

356°F = 453.15 K

Common European baking temperature. US recipes might say 350°F (close but slightly cooler). For best results, use the recipe's original units when possible; convert only when necessary.

Absolute zero

Input

0 K

Output

-273.15°C = -459.67°F = 0°R

The lowest theoretically possible temperature. Useful reference for understanding thermal energy in physics. Note Rankine starts at absolute zero too (like Kelvin), just uses Fahrenheit-sized degrees.

Tips & Best Practices for Temperature Converter

1.Memorize key reference points: 0°C = 32°F (water freezes), 100°C = 212°F (water boils), 20°C = 68°F (room temp), 37°C = 98.6°F (body temp).
2.For scientific work, default to Kelvin. Negative temperatures cause issues in many physics formulas; Kelvin avoids them entirely.
3.Cooking can be approximate; science cannot. Convert oven temperatures with 1-2 decimals; convert lab temperatures with full precision.
4.Be aware of temperature scale notation: write '37°C' not '37C'. The degree symbol distinguishes temperature from other quantities.
5.For weather: warm/comfortable = 20-25°C / 68-77°F. Hot = 30°C+ / 86°F+. Cold = below 0°C / 32°F. Useful frame of reference for travel.
6.Wind chill and heat index are different from raw temperature — they incorporate wind/humidity. The converter handles raw temperatures only.

Frequently Asked Questions

All major scales: Celsius (°C, used in most of the world), Fahrenheit (°F, used in US), Kelvin (K, scientific), and Rankine (°R, engineering, US). Plus historical scales: Réaumur (used in Europe centuries ago) and Newton (rare). The calculator converts between any two scales.

Temperature Converter

How to Use Temperature Converter

Enter temperature

Choose target scale

Verify special points

Use for context

When to Use Temperature Converter

Cooking and baking

Weather across regions

Scientific work

Health and medical contexts

Temperature Converter Examples

Common temperatures

Cooking conversion

Absolute zero

Tips & Best Practices for Temperature Converter

Frequently Asked Questions

Related Tools

Length Converter

Weight Converter

Area Converter

Volume Converter

Data Size Converter

Roman Numeral Converter