Temperature Converter.
Convert between Celsius, Fahrenheit, Kelvin, and Rankine simultaneously. Edit any temperature field and all four scales update in real time.
Edit any field — all four scales update instantly.
Water freezes at 0°C, boils at 100°C
Water freezes at 32°F, boils at 212°F
Absolute zero = 0 K, used in physics & chemistry
Absolute scale using Fahrenheit degrees
Common Reference Points
Processed on our server. What you enter is sent over an encrypted connection, calculated, and returned. It is never written to a database or logged, and nothing is retained once the result is sent. Avoid entering passwords, API keys or other secrets. How we handle data
Four Temperature Scales
Celsius and Fahrenheit are everyday scales. Kelvin and Rankine are absolute scales used in thermodynamics and physics — they start at absolute zero and have no negative values, making them essential for scientific calculations like the Ideal Gas Law (PV = nRT).
Exact Conversion Formulas
°F = (°C × 9/5) + 32 | K = °C + 273.15 | °R = (°C + 273.15) × 9/5. All conversions are exact — there is no rounding in the formulas, only in the display output (4 decimal places).
Temperature Scales in Science and Daily Life Methodology.
The Calculation Branch
Industrial Standards.
Each field calculates by first converting to Celsius, then applying the target formula. This gives bidirectional conversion with maximum precision. Kelvin inputs below -273.15 (absolute zero) are mathematically invalid and will produce out-of-range values.
In-Depth Analysis & Reference Data
Important temperature benchmarks: -273.15°C / -459.67°F = Absolute Zero | -40°C = -40°F (the crossover point) | 0°C / 32°F = Water freezes | 20°C / 68°F = Room temperature | 37°C / 98.6°F = Human body temperature | 100°C / 212°F = Water boils at sea level | 232°C / 450°F = Tin melts | 660°C / 1220°F = Aluminium melts | 1538°C / 2800°F = Iron melts
Registry Questions & FAQ.
Why does water boil at different temperatures at altitude?
Water boils when vapor pressure equals atmospheric pressure. At higher altitudes, atmospheric pressure is lower, so water boils at lower temperatures. In Denver (5,280 ft), water boils at about 95°C (203°F). On Everest, it boils at roughly 70°C (158°F) — not hot enough to properly cook rice or pasta.
When would I use Kelvin instead of Celsius?
Kelvin is used in thermodynamics (Ideal Gas Law, Carnot efficiency), astrophysics (star temperatures in millions of K), color temperature in photography and lighting (warm bulbs ≈ 2700K, daylight ≈ 5500K), and chemistry (reaction rate equations). Any formula where temperature appears in a ratio or multiplication requires Kelvin.
Estimates for planning. Always confirm against an authoritative source.