Validated absolute-temperature conversion
Temperature Converter
Convert an absolute temperature between degrees Celsius, degrees Fahrenheit, kelvins and degrees Rankine. Inputs below absolute zero are rejected instead of being reported as physical temperatures.
Strict absolute-zero limitDecimal point or commaNo hidden state
Absolute temperature only. Do not use this offset conversion for a temperature difference or interval. For intervals, 1 °C has the same magnitude as 1 K, while 1 °F and 1 °R each have the magnitude 5/9 K.
Equivalent absolute temperatures
Celsius temperature
Fahrenheit temperature
Thermodynamic temperature
Rankine temperature
Method, formulas and boundaries
Canonical thermodynamic temperature T in K:
from °C: T/K = t/°C + 273.15
from °F: T/K = (t/°F + 459.67) × 5/9
from °R: T/K = (T/°R) × 5/9
from °C: T/K = t/°C + 273.15
from °F: T/K = (t/°F + 459.67) × 5/9
from °R: T/K = (T/°R) × 5/9
Outputs:
t/°C = T/K − 273.15
t/°F = (T/K) × 9/5 − 459.67
T/°R = (T/K) × 9/5
Accepted
- Absolute temperatures at or above 0 K.
- Point or comma decimal marker.
- Normalized T no greater than 1012 K.
Rejected
- Any value below absolute zero.
- Exponent,grouping or unit suffix.
- Temperature intervals/differences.
Precision
- Up to 12 significant digits displayed.
- No claim beyond source measurement uncertainty.
- Conversion does not calibrate a sensor.
Reference checks. Absolute zero is 0 K = −273.15 °C = −459.67 °F = 0 °R. The Celsius and Fahrenheit numerical values are equal at −40. Water phase-transition temperatures are intentionally not used as unconditional reference points because they depend on stated conditions and realization.
Sources
- BIPM, The International System of Units (SI Brochure), 9th edition,version 4.01,June 2026, page 129: defines the kelvin and the relation t/°C = T/K − 273.15; it also distinguishes absolute temperatures from temperature differences.
- NIST Special Publication 811, Appendix B.8: gives the Celsius/Kelvin,Fahrenheit/Celsius,Fahrenheit/Kelvin and Rankine/Kelvin conversion equations and interval factors.
- NIST, Kelvin: Thermodynamic Temperature: describes thermodynamic temperature as a number of kelvins above absolute zero,the theoretical lower bound.
Classification: these are published unit-conversion relations,not empirical recommendations or an ISO calculator. Results remain limited by the original measurement,scale realization and uncertainty.
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