How do you convert Celsius to Fahrenheit?

Multiply by 9/5, then add 32. Formula: °F = °C × 9/5 + 32. For example, 100°C = 212°F.

What is absolute zero?

Absolute zero is the lowest possible temperature: 0 K = −273.15°C = −459.67°F = 0°R. It represents the point where molecular motion reaches its minimum.

What is the Rankine scale?

The Rankine scale (°R) is an absolute temperature scale based on Fahrenheit intervals, where 0°R = absolute zero. Used in American engineering thermodynamics. °R = °F + 459.67.

When should I use Kelvin vs Celsius?

Use Kelvin in thermodynamic calculations (gas laws, radiation, Carnot cycle) and scientific work. Use Celsius for everyday engineering, HVAC, and when working with temperature differences (ΔC = ΔK).

What temperature is the same in °C and °F?

−40° is the same in both scales: −40°C = −40°F. This can be derived by solving °F = °C × 9/5 + 32 with °F = °C.

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Temperature Converter

Instantly convert between Celsius, Fahrenheit, Kelvin, and Rankine. All four values displayed simultaneously.

°C ↔ °F ↔ K ↔ °RInstant#179

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Celsius

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Fahrenheit

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Kelvin

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Rankine

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Conversion Formulas

Kelvin and Rankine are absolute scales (0 = absolute zero). Celsius and Fahrenheit are relative scales with offset zero points.

Key Reference Points

Absolute zero: 0 K = −273.15°C = −459.67°F = 0°R
Water freezing: 273.15 K = 0°C = 32°F = 491.67°R
Water boiling: 373.15 K = 100°C = 212°F = 671.67°R

Temperature Converter | °C ↔ °F ↔ K ↔ °R | Free Online Tool

Published by Nikolai Shelkovenko on February 15, 2026 February 15, 2026

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Conversion Formulas

Key Reference Points