# Temperature Converter

Free temperature converter. Convert between Celsius, Fahrenheit, and Kelvin instantly using exact formulas. See all three temperature scales at once.

## What this calculates

Convert temperatures between Celsius, Fahrenheit, and Kelvin with exact formulas. This calculator shows the precise conversion and displays the temperature in all three scales simultaneously.

## Inputs

- **Temperature**
- **From** — options: Celsius (°C), Fahrenheit (°F), Kelvin (K)
- **To** — options: Celsius (°C), Fahrenheit (°F), Kelvin (K)

## Outputs

- **Result** — The converted temperature value.
- **Formula** — formatted as text — The conversion formula used.
- **All Conversions** — formatted as text — The temperature expressed in all three scales.

## Details

Temperature conversion is essential in science, cooking, weather, and international travel. Unlike other unit conversions, temperature scales are not related by simple multiplication -- they involve offsets.

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

Key Reference Points

- Water freezes: 0°C = 32°F = 273.15K

- Water boils: 100°C = 212°F = 373.15K

- Absolute zero: -273.15°C = -459.67°F = 0K

- Body temperature: 37°C = 98.6°F = 310.15K

- The scales intersect at -40: -40°C = -40°F

## Frequently Asked Questions

**Q: How do I convert Celsius to Fahrenheit?**

A: Multiply the Celsius temperature by 9/5 (or 1.8), then add 32. For example, 25°C = (25 × 9/5) + 32 = 45 + 32 = 77°F. A quick mental shortcut: double the Celsius value and add 30 for a rough estimate.

**Q: What is absolute zero?**

A: Absolute zero is the lowest possible temperature, where all molecular motion ceases. It is exactly 0 Kelvin, which equals -273.15°C or -459.67°F. It cannot be physically achieved but can be approached extremely closely in laboratories.

**Q: Why do Celsius and Fahrenheit intersect at -40?**

A: Setting °C = °F in the formula °F = (°C × 9/5) + 32, we get °C = (°C × 9/5) + 32, which solves to °C = -40. This is the unique temperature where both scales read the same value: -40°C = -40°F.

**Q: What is the Kelvin scale used for?**

A: The Kelvin scale is the SI unit of temperature used in science and engineering. It starts at absolute zero (0K) and uses the same degree size as Celsius. It is essential in thermodynamics, gas laws, and any calculation requiring an absolute temperature scale.

---

Source: https://vastcalc.com/calculators/conversion/temperature-converter
Category: Conversion
Last updated: 2026-04-21