Conversor de temperatura
Convierte al instante entre Celsius, Fahrenheit, Kelvin y Rankine, con el cálculo paso a paso y una tabla de referencia de temperaturas clave.
Cómo usar esta calculadora
- 1Enter the temperature you have.
- 2Choose the scale it is in and the scale you want.
- 3All four scales are shown at once, so you never need a second conversion.
Cómo funciona
Fórmulas de conversión de temperatura
°F = °C × 9/5 + 32 °C = (°F − 32) × 5/9 K = °C + 273,15 °R = °F + 459,67 °C = K − 273,15
Convertir temperaturas exige ajustar dos cosas: el punto cero de cada escala y el tamaño de sus grados. Celsius y Kelvin comparten el tamaño de grado pero difieren en el cero (273,15); Fahrenheit y Rankine hacen lo mismo entre sí. Por eso pasar de Celsius a Fahrenheit no basta con multiplicar: hay que escalar por 9/5 y luego desplazar el cero sumando 32.
Ejemplo resuelto
20 °C equivalen a 20 × 9/5 + 32 = 68 °F, o a 20 + 273,15 = 293,15 K. A la inversa, 98,6 °F son (98,6 − 32) × 5/9 = 37 °C, la temperatura corporal normal.
Conversor de temperatura: la guía completa
The mental shortcut for Celsius and Fahrenheit
The exact conversion is × 1.8 + 32, which is awkward in your head. The usual approximation — double it and add 30 — is accurate to within a couple of degrees across normal weather temperatures. 20 °C becomes 70 °F by the shortcut and 68 °F exactly; 30 °C becomes 90 °F by the shortcut and 86 °F exactly.
A few anchor points are worth memorising outright: 0 °C is 32 °F, 10 °C is 50 °F, 20 °C is 68 °F, 30 °C is 86 °F, and 37 °C is 98.6 °F. Everything between can be interpolated well enough for practical purposes.
−40 is the one point where the two scales agree exactly. It is the only such point, because the two lines have different slopes and can only cross once.
Why Kelvin has no degree sign
Kelvin is an absolute scale: its zero is absolute zero, the temperature at which all classical thermal motion stops. Because there is no arbitrary offset, kelvin values are proportional — 200 K really is twice as hot as 100 K in a way that 200 °C is not twice 100 °C.
That is why the SI unit is written as "300 K", not "300 °K". The degree symbol marks a scale with an arbitrary zero, and kelvin does not have one. All the gas laws, blackbody radiation, and thermodynamic equations require kelvin for exactly this reason.
Rankine is the same idea applied to Fahrenheit degrees: absolute zero is 0 °R, and water freezes at 491.67 °R. It survives in some American engineering fields, particularly aerospace and HVAC.
Converting a difference is not converting a value
This trips up thermostat specifications, engineering tolerances, and weather reports alike. A temperature of 5 °C is 41 °F. But a temperature difference of 5 °C is a difference of 9 °F — you multiply by 1.8 and skip the offset entirely.
The rule: use the full formula for a point on the scale, and only the ratio for an interval. Since a kelvin and a Celsius degree are the same size, a temperature difference in °C and in K is numerically identical, which is why heat-transfer equations quote units as W/(m·K) without ambiguity.
Preguntas frecuentes
¿Cómo se pasa de Celsius a Fahrenheit?
Multiplica los grados Celsius por 9/5 (o 1,8) y suma 32. Por ejemplo, 20 °C × 1,8 + 32 = 68 °F. Para el camino inverso, resta 32 y multiplica por 5/9.
¿Qué es el cero absoluto?
Es la temperatura más baja posible: 0 K, equivalente a −273,15 °C o −459,67 °F. En ese punto cesa el movimiento térmico de las partículas. Las escalas Kelvin y Rankine parten de ahí, por lo que nunca tienen valores negativos.
¿Por qué la conversión no es una simple multiplicación?
Porque las escalas no comparten el mismo punto cero. Convertir un valor de temperatura implica escalar y luego desplazar el cero, mientras que convertir una diferencia solo requiere escalar. Por eso 1 °C de diferencia son 1,8 °F, pero el valor 1 °C es 33,8 °F.