Kelvins (K)
The kelvin (K) is the SI base unit of temperature.
Convert kelvins to any temperature unit
328 kelvins = 54.85 degrees Celsius
Quick facts
- Unit
- Kelvin (plural: kelvins)
- Symbol
- K
- Measures
- Temperature
- System
- Common scales
- Definition
- Defined by fixing the Boltzmann constant k at exactly 1.380649 × 10⁻²³ J/K (since 2019).
- Also written
- degrees kelvin, absolute temperature
1 kelvin in other units
| Degrees Celsius | -272.15 °C |
| Degrees Fahrenheit | -457.87 °F |
| Gas marks | -6.5787 GM |
| Degrees Rankine | 1.8 °R |
| Degrees Réaumur | -217.72 °Ré |
What is a kelvin?
The kelvin (K) is the SI base unit of temperature. Its scale starts at absolute zero, the lowest temperature possible, where particles have the minimum energy allowed by quantum mechanics. Because the scale has no negative values, it is the one used in physics and chemistry formulas such as the gas laws.
A change of one kelvin equals a change of one degree Celsius: 0 °C is 273.15 K and 100 °C is 373.15 K. Kelvins are written without a degree sign.
What kelvins are used for
- Physics, chemistry and astronomy
- Color temperature of light bulbs and camera white balance (2700 K warm, 6500 K daylight)
- Cryogenics and superconductivity
- Thermodynamics and engineering calculations
Kelvins in real life
- Absolute zero is 0 K
- Liquid nitrogen boils at 77 K
- Room temperature is about 293 K
- The surface of the Sun is about 5,772 K
- Warm white LED bulbs are 2,700 K
History of the kelvin
William Thomson (Lord Kelvin) proposed an absolute temperature scale in 1848. The unit was called the "degree Kelvin" until 1967, when it became simply the kelvin. It was redefined in 2019 by fixing the Boltzmann constant.
Top kelvin conversions
Common amounts of kelvins
- 0 K
- 1 K
- 2 K
- 3 K
- 4 K
- 5 K
- 10 K
- 20 K
- 50 K
- 77 K
- 100 K
- 150 K
- 200 K
- 250 K
- 260 K
- 261 K
- 262 K
- 263 K
- 264 K
- 265 K
- 266 K
- 267 K
- 268 K
- 269 K
- 270 K
- 271 K
- 272 K
- 273 K
- 274 K
- 275 K
- 276 K
- 277 K
- 278 K
- 279 K
- 280 K
- 281 K
- 282 K
- 283 K
- 284 K
- 285 K
- 286 K
- 287 K
- 288 K
- 289 K
- 290 K
- 291 K
- 292 K
- 293 K
- 294 K
- 295 K
- 296 K
- 297 K
- 298 K
- 299 K
- 300 K
- 301 K
- 302 K
- 303 K
- 304 K
- 305 K
- 306 K
- 307 K
- 308 K
- 309 K
- 310 K
- 311 K
- 312 K
- 313 K
- 314 K
- 315 K
- 316 K
- 317 K
- 318 K
- 319 K
- 320 K
- 321 K
- 322 K
- 323 K
- 324 K
- 325 K
- 326 K
- 327 K
- 328 K
- 329 K
- 330 K
- 331 K
- 332 K
- 333 K
- 334 K
- 335 K
- 336 K
- 337 K
- 338 K
- 339 K
- 340 K
- 341 K
- 342 K
- 343 K
- 344 K
- 345 K
- 346 K
- 347 K
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- 349 K
- 350 K
- 351 K
- 352 K
- 353 K
- 354 K
- 355 K
- 356 K
- 357 K
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- 359 K
- 360 K
- 361 K
- 362 K
- 363 K
- 364 K
- 365 K
- 366 K
- 367 K
- 368 K
- 369 K
- 370 K
- 371 K
- 372 K
- 373 K
- 374 K
- 375 K
- 376 K
- 377 K
- 378 K
- 379 K
- 380 K
- 381 K
- 382 K
- 383 K
- 384 K
- 385 K
- 386 K
- 387 K
- 388 K
- 389 K
- 390 K
- 391 K
- 392 K
- 393 K
- 394 K
- 395 K
- 396 K
- 397 K
- 398 K
- 399 K
- 400 K
- 450 K
- 500 K
- 600 K
- 1,000 K
- 1,500 K
- 2,000 K
- 5,000 K
- 5,778 K
- 10,000 K
Convert kelvins to all 16 other units
Common scales
Historical scales
Scientific
Convert to kelvins
Frequently asked questions
What is a kelvin?
The kelvin (K) is the SI base unit of temperature.
How is the kelvin defined?
Defined by fixing the Boltzmann constant k at exactly 1.380649 × 10⁻²³ J/K (since 2019).
How many degrees Celsius are in a kelvin?
One kelvin equals -272.15 degrees Celsius.
How many degrees Fahrenheit are in a kelvin?
One kelvin equals -457.87 degrees Fahrenheit.
How many gas marks are in a kelvin?
One kelvin equals -6.5787 gas marks.