Kelvin (K) es la escala de temperatura absoluta del Sistema Internacional. A diferencia de Celsius y Fahrenheit, empieza en el cero absoluto (0 K), donde todo movimiento térmico cesa. Aquí tienes las fórmulas exactas, tabla amplia, truco mental y los usos clave: ciencia, temperatura de color (iluminación/fotografía) y criogenia.
Por qué Kelvin es especial
| Escala | Cero | Tamaño del grado | Símbolo |
|---|---|---|---|
| Kelvin | Cero absoluto (0 K) | 1 K = 1 °C | K (sin °) |
| Celsius | Agua hiela (0 °C) | 1 °C = 1 K | °C |
| Fahrenheit | Mezcla hielo/sal (0 °F) | 1 °F = 5/9 K | °F |
0 K = −273.15 °C = −459.67 °F (cero absoluto).
273.15 K = 0 °C = 32 °F (hielo).
373.15 K = 100 °C = 212 °F (ebullición agua).
Fórmulas exactas
Kelvin ↔ Celsius (offset fijo)
°C = K − 273.15
K = °C + 273.15
Kelvin ↔ Fahrenheit (vía Celsius)
°F = (K − 273.15) × 1.8 + 32
K = (°F − 32) / 1.8 + 273.15
Tabla de referencia (K → °C → °F)
| K | °C | °F | Contexto |
|---|---|---|---|
| 0 | -273.15 | -459.67 | Cero absoluto |
| 1 | -272.15 | -457.87 | Helio líquido (ebullición 4.2 K) |
| 4.2 | -268.95 | -452.11 | Helio-4 hierve (criogenia) |
| 20 | -253.15 | -423.67 | Hidrógeno líquido (ebullición 20.3 K) |
| 77.4 | -195.75 | -320.35 | Nitrógeno líquido (LN₂) |
| 90.2 | -182.95 | -297.31 | Oxígeno líquido (LOX) |
| 111.7 | -161.45 | -258.61 | Metano líquido (LNG) |
| 194.7 | -78.45 | -109.21 | Hielo seco (CO₂ sublima) |
| 273.15 | 0.00 | 32.00 | Agua hiela |
| 293.15 | 20.00 | 68.00 | Ambiente confort |
| 310.15 | 37.00 | 98.60 | Cuerpo humano |
| 373.15 | 100.00 | 212.00 | Agua hierve |
| 450 | 176.85 | 350.33 | Horno bajo |
| 500 | 226.85 | 440.33 | Pizza napolitana |
| 573 | 299.85 | 571.73 | Horno alto |
| 1000 | 726.85 | 1340.33 | Acero al rojo |
| 2000 | 1726.85 | 3140.33 | Llama vela / tungsteno |
| 3000 | 2726.85 | 4940.33 | Bombilla halógena |
| 5500 | 5226.85 | 9440.33 | Luz diurna (temp. color) |
| 6500 | 6226.85 | 11240.33 | Luz día nublada / monitor sRGB |
| 10000 | 9726.85 | 17540.33 | Cielo azul profundo |
Temperatura de color (iluminación, fotografía, pantallas)
La temperatura de color se expresa en Kelvin (cuerpo negro ideal). No es temperatura térmica, es el color de la luz.
| K | Apariencia | Uso típico |
|---|---|---|
| 1700–1900 | Rojo/ámbar intenso | Vela, llama |
| 2000–2500 | Naranja cálido | Bombilla vintage, atardecer |
| 2700–3000 | Blanco cálido | Hogar, restaurantes, “warm white” |
| 3500–4100 | Blanco neutro | Oficinas, comercios, “neutral white” |
| 5000–5500 | Blanco día (D50/D55) | Artes gráficas, fotografía, “daylight” |
| 6000–6500 | Blanco frío / Luz día | Monitores sRGB, exterior nublado, “cool white” |
| 7000–10000 | Azulado | Sombra, cielo azul, “north light” |
Regla: K bajo = cálido (rojo/ámbar); K alto = frío (azul).
En LED: “2700 K” = cálido; “6500 K” = frío.
Criogenia: hitos de ebullición (1 atm)
| Sustancia | K | °C | Uso |
|---|---|---|---|
| Helio-4 | 4.22 | -268.93 | Superconductores, cuántica |
| Hidrógeno | 20.27 | -252.88 | Combustible cohetes |
| Neón | 27.10 | -246.05 | Criogenia especializada |
| Nitrógeno | 77.36 | -195.79 | LN₂ (congelación rápida, dermatología, overclocking) |
| Oxígeno | 90.19 | -182.96 | LOX (cohetes, médico) |
| Argón | 87.30 | -185.85 | Soldadura, aislamiento |
| Metano | 111.65 | -161.50 | LNG (transporte gas) |
Truco mental
°C ≈ K − 273 (error 0.15 °C, despreciable salvo metrología fina)
| K | Truco °C | Exacto °C |
|---|---|---|
| 300 | 27 | 26.85 |
| 293 | 20 | 19.85 |
| 310 | 37 | 36.85 |
| 5500 | 5227 | 5226.85 |
Para temperatura de color (2000–10000 K) la aproximación basta.
Conclusión
- Kelvin = escala absoluta (0 K = cero absoluto). No usa “grados”.
- K ↔ °C: suma/resta 273.15 (mismo tamaño de grado).
- K ↔ °F: vía Celsius.
- Color temp: se expresa en K (2700 K cálido, 6500 K frío).
- Criogenia: LN₂ 77 K, LOX 90 K, LNG 111 K.
- Herramienta: conversor de unidades — elige “Temperatura” y convierte K ↔ °C ↔ °F al instante.
Kelvin (K) is the absolute temperature scale of the International System. Unlike Celsius and Fahrenheit, it starts at absolute zero (0 K), where all thermal motion ceases. Here you have the exact formulas, wide table, mental trick and key uses: science, color temperature (lighting/photography) and cryogenics.
Why Kelvin is special
| Scale | Zero | Degree size | Symbol |
|---|---|---|---|
| Kelvin | Absolute zero (0 K) | 1 K = 1 °C | K (no °) |
| Celsius | Water freezes (0 °C) | 1 °C = 1 K | °C |
| Fahrenheit | Ice/salt mix (0 °F) | 1 °F = 5/9 K | °F |
0 K = −273.15 °C = −459.67 °F (absolute zero).
273.15 K = 0 °C = 32 °F (ice).
373.15 K = 100 °C = 212 °F (water boils).
Exact formulas
Kelvin ↔ Celsius (fixed offset)
°C = K − 273.15
K = °C + 273.15
Kelvin ↔ Fahrenheit (via Celsius)
°F = (K − 273.15) × 1.8 + 32
K = (°F − 32) / 1.8 + 273.15
Reference table (K → °C → °F)
| K | °C | °F | Context |
|---|---|---|---|
| 0 | -273.15 | -459.67 | Absolute zero |
| 1 | -272.15 | -457.87 | Liquid helium (boils at 4.2 K) |
| 4.2 | -268.95 | -452.11 | Helium-4 boils (cryogenics) |
| 20 | -253.15 | -423.67 | Liquid hydrogen (boils at 20.3 K) |
| 77.4 | -195.75 | -320.35 | Liquid nitrogen (LN₂) |
| 90.2 | -182.95 | -297.31 | Liquid oxygen (LOX) |
| 111.7 | -161.45 | -258.61 | Liquid methane (LNG) |
| 194.7 | -78.45 | -109.21 | Dry ice (CO₂ sublimates) |
| 273.15 | 0.00 | 32.00 | Water freezes |
| 293.15 | 20.00 | 68.00 | Room comfort |
| 310.15 | 37.00 | 98.60 | Human body |
| 373.15 | 100.00 | 212.00 | Water boils |
| 450 | 176.85 | 350.33 | Low oven |
| 500 | 226.85 | 440.33 | Neapolitan pizza |
| 573 | 299.85 | 571.73 | High oven |
| 1000 | 726.85 | 1340.33 | Red-hot steel |
| 2000 | 1726.85 | 3140.33 | Candle flame / tungsten |
| 3000 | 2726.85 | 4940.33 | Halogen bulb |
| 5500 | 5226.85 | 9440.33 | Daylight (color temp) |
| 6500 | 6226.85 | 11240.33 | Overcast daylight / sRGB monitor |
| 10000 | 9726.85 | 17540.33 | Deep blue sky |
Color temperature (lighting, photography, screens)
Color temperature is expressed in Kelvin (ideal black body). It’s not thermal temperature, it’s the color of light.
| K | Appearance | Typical use |
|---|---|---|
| 1700–1900 | Deep red/amber | Candle, flame |
| 2000–2500 | Warm orange | Vintage bulb, sunset |
| 2700–3000 | Warm white | Home, restaurants, “warm white” |
| 3500–4100 | Neutral white | Offices, retail, “neutral white” |
| 5000–5500 | Daylight (D50/D55) | Graphic arts, photography, “daylight” |
| 6000–6500 | Cool white / Daylight | sRGB monitors, overcast, “cool white” |
| 7000–10000 | Bluish | Shade, blue sky, “north light” |
Rule: Low K = warm (red/amber); High K = cool (blue).
In LED: “2700 K” = warm; “6500 K” = cool.
Cryogenics: boiling points (1 atm)
| Substance | K | °C | Use |
|---|---|---|---|
| Helium-4 | 4.22 | -268.93 | Superconductors, quantum |
| Hydrogen | 20.27 | -252.88 | Rocket fuel |
| Neon | 27.10 | -246.05 | Specialized cryogenics |
| Nitrogen | 77.36 | -195.79 | LN₂ (flash freezing, dermatology, overclocking) |
| Oxygen | 90.19 | -182.96 | LOX (rockets, medical) |
| Argon | 87.30 | -185.85 | Welding, insulation |
| Methane | 111.65 | -161.50 | LNG (gas transport) |
Mental trick
°C ≈ K − 273 (error 0.15 °C, negligible except precision metrology)
| K | Trick °C | Exact °C |
|---|---|---|
| 300 | 27 | 26.85 |
| 293 | 20 | 19.85 |
| 310 | 37 | 36.85 |
| 5500 | 5227 | 5226.85 |
For color temperature (2000–10000 K) the approximation is enough.
Conclusion
- Kelvin = absolute scale (0 K = absolute zero). No “degrees”.
- K ↔ °C: add/subtract 273.15 (same degree size).
- K ↔ °F: via Celsius.
- Color temp: expressed in K (2700 K warm, 6500 K cool).
- Cryogenics: LN₂ 77 K, LOX 90 K, LNG 111 K.
- Tool: unit converter — pick “Temperature” and convert K ↔ °C ↔ °F instantly.