Temperature Converter

Convert temperature between Celsius (°C), Fahrenheit (°F), Kelvin (K), Rankine (°R), and Réaumur (°Ré) with visual thermometer display, reference points, and detailed conversion formulas.

Free to useNo sign-up requiredUpdated Jan 2026

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About Temperature Converter

Welcome to the Temperature Converter, a comprehensive tool for converting temperatures between Celsius (°C), Fahrenheit (°F), Kelvin (K), Rankine (°R), and Réaumur (°Ré). Whether you are cooking, studying science, checking weather in different countries, or working on engineering projects, this converter provides instant, accurate results with visual feedback and helpful reference points.

Temperature Scales Explained

Celsius (°C) - The Scientific Standard

Celsius, also known as centigrade, is the most widely used temperature scale globally. It was developed by Anders Celsius in 1742 and is based on the freezing point (0°C) and boiling point (100°C) of water at standard atmospheric pressure. Celsius is used in everyday life in most countries and is the standard in scientific research.

Fahrenheit (°F) - The American Standard

Fahrenheit was developed by Daniel Gabriel Fahrenheit in 1724. On this scale, water freezes at 32°F and boils at 212°F. It is primarily used in the United States, the Bahamas, Belize, the Cayman Islands, and Palau. The Fahrenheit scale provides more granularity for everyday temperatures, with 180 degrees between freezing and boiling.

Kelvin (K) - The Absolute Scale

Kelvin is the SI (International System of Units) base unit of temperature. It starts at absolute zero (-273.15°C), the theoretical point where all molecular motion stops. Kelvin uses the same increment size as Celsius (1K = 1°C) but has no negative values. It is essential in physics, chemistry, and astronomy.

Rankine (°R) - The Engineering Scale

Rankine is an absolute temperature scale like Kelvin but uses Fahrenheit-sized degrees. It starts at absolute zero (0°R = -459.67°F). Rankine is primarily used in American engineering for thermodynamic calculations, particularly in the aerospace and chemical engineering industries.

Réaumur (°Ré) - The Historical Scale

Réaumur was introduced by René Antoine Ferchault de Réaumur in 1730. On this scale, water freezes at 0°Ré and boils at 80°Ré. While largely obsolete today, it was once widely used in Europe and is still referenced in some historical contexts and cheesemaking.

Conversion Formulas

Celsius to Other Units

Celsius Conversions

$$°F = (°C \times \frac{9}{5}) + 32$$ $$K = °C + 273.15$$ $$°R = (°C + 273.15) \times \frac{9}{5}$$ $$°Ré = °C \times 0.8$$

Fahrenheit to Other Units

Fahrenheit Conversions

$$°C = (°F - 32) \times \frac{5}{9}$$ $$K = (°F - 32) \times \frac{5}{9} + 273.15$$ $$°R = °F + 459.67$$ $$°Ré = (°F - 32) \times \frac{4}{9}$$

Kelvin to Other Units

Kelvin Conversions

$$°C = K - 273.15$$ $$°F = (K - 273.15) \times \frac{9}{5} + 32$$ $$°R = K \times \frac{9}{5}$$ $$°Ré = (K - 273.15) \times 0.8$$

Common Temperature Reference Points

Reference Point	Celsius	Fahrenheit	Kelvin	Rankine
Absolute Zero	-273.15°C	-459.67°F	0 K	0°R
Water Freezing	0°C	32°F	273.15 K	491.67°R
Room Temperature	20°C	68°F	293.15 K	527.67°R
Human Body	37°C	98.6°F	310.15 K	558.27°R
Water Boiling	100°C	212°F	373.15 K	671.67°R

How to Use This Converter

Enter the temperature: Type your temperature value in the input field. Decimals and negative numbers are supported.
Select the source unit: Choose the unit of your input temperature from the dropdown menu.
Click Convert: Press the button to instantly convert to all five temperature scales.
View results: See the visual thermometer, temperature category, conversions to all units, and comparisons with common reference points.

Quick Reference: Temperature Ranges

Extremely Cold (below -40°C/-40°F): Polar regions, extreme weather events
Freezing (0°C/32°F to -40°C): Winter conditions, frozen food storage
Cold (0-10°C/32-50°F): Refrigerator temperature, cool autumn days
Cool (10-20°C/50-68°F): Spring and fall weather, wine storage
Comfortable (20-25°C/68-77°F): Ideal room temperature
Warm (25-35°C/77-95°F): Summer weather, warm climate
Hot (35-45°C/95-113°F): Heat waves, hot deserts
Very Hot (above 45°C/113°F): Extreme heat, dangerous conditions

Interesting Temperature Facts

-40° is the same in both Celsius and Fahrenheit (-40°C = -40°F)
Absolute zero (0 K or -273.15°C) is the theoretical lowest temperature possible
The Sun's surface is approximately 5,500°C (9,932°F)
The coldest temperature recorded on Earth was -89.2°C (-128.6°F) in Antarctica
The hottest temperature recorded on Earth was 56.7°C (134°F) in Death Valley, USA

Frequently Asked Questions

How do I convert Celsius to Fahrenheit?

To convert Celsius to Fahrenheit, multiply the Celsius temperature by 9/5 (or 1.8) and add 32. The formula is: °F = (°C × 9/5) + 32. For example, 25°C = (25 × 1.8) + 32 = 77°F.

What is the difference between Celsius and Kelvin?

Kelvin and Celsius have the same scale increment (1K = 1°C), but different zero points. Kelvin starts at absolute zero (-273.15°C), while Celsius uses water's freezing point as 0°C. To convert: K = °C + 273.15. Kelvin is used in scientific contexts because it has no negative values.

What is absolute zero?

Absolute zero is the lowest possible temperature where all molecular motion theoretically stops. It equals -273.15°C, -459.67°F, 0 K, and 0°R. No physical system can reach absolute zero, though scientists have achieved temperatures within billionths of a degree of it.

Why does the US use Fahrenheit instead of Celsius?

The US uses Fahrenheit for historical reasons. Daniel Fahrenheit created his scale in 1724, before Celsius (1742). While most countries adopted the metric system including Celsius, the US retained Fahrenheit for everyday use. Fahrenheit offers more granularity for weather temperatures (0-100°F covers typical weather), while Celsius is standard in science worldwide.

What temperature is the same in Celsius and Fahrenheit?

-40 degrees is the same in both Celsius and Fahrenheit (-40°C = -40°F). This is the only point where the two scales intersect. You can verify this using the conversion formula: (-40 × 9/5) + 32 = -72 + 32 = -40.

What is the Rankine temperature scale?

Rankine is an absolute temperature scale like Kelvin, but uses Fahrenheit-sized degrees instead of Celsius-sized degrees. It starts at absolute zero (0°R = -459.67°F). Rankine is primarily used in American engineering for thermodynamic calculations. To convert: °R = °F + 459.67 or °R = K × 9/5.

Related Resources

Reference this content, page, or tool as:

"Temperature Converter" at https://MiniWebtool.com/temperature-converter/ from MiniWebtool, https://MiniWebtool.com/

by miniwebtool team. Updated: Jan 30, 2026

Developer API available: Run this tool from your app, automation, or agent with one JSON HTTP request. View API docs