Celsius to Rankine Converter
Quick Conversion: R = (C + 273.15) × 9/5
Celsius to Rankine Converter
What Is Celsius?
The degree Celsius (°C) is the SI-derived unit of temperature. The freezing point of water is 0°C and the boiling point is 100°C. It is the global standard for everyday and scientific temperature measurement.
What Is Rankine?
The degree Rankine (°R) is an absolute temperature scale using Fahrenheit-sized increments. Zero Rankine equals absolute zero (−273.15°C or −459.67°F). Proposed in 1859 by Scottish engineer William Rankine, it is used in US thermodynamics, particularly for the Rankine cycle in steam engines and power plants.
Celsius to Rankine Formula
The formula is:
°R = (°C + 273.15) × 9/5
This is a two-step process: first convert Celsius to Kelvin (+273.15), then convert the Kelvin-sized degree to Fahrenheit-sized degree (×9/5). Since Rankine is "absolute Fahrenheit," this makes sense.
Worked Example
Convert 100°C (boiling water) to Rankine:
- Add: 100 + 273.15 = 373.15
- Scale: 373.15 × 9/5 = 671.67°R
So boiling water is 671.67°R — a value commonly used as a reference in engineering thermodynamics.
Reference Table: Engineering Reference Points
| °C | °R | Context |
|---|---|---|
| −273.15 | 0 | Absolute zero |
| 0 | 491.67 | Water freezes (= 32°F + 459.67) |
| 15 | 518.67 | Standard conditions (ISA) |
| 20 | 527.67 | Room temperature |
| 25 | 536.67 | Standard temperature (chemistry) |
| 100 | 671.67 | Water boils |
| 500 | 1,391.67 | Steam turbine inlet (typical) |
Rankine vs Kelvin — When to Use Which?
Both are absolute scales (zero = absolute zero), but they use different degree sizes. Kelvin uses Celsius-sized degrees and is the SI standard — used worldwide in science and engineering. Rankine uses Fahrenheit-sized degrees and appears in US engineering traditions, particularly in thermodynamics textbooks, HVAC, and the Rankine steam cycle. If your reference data is in Fahrenheit, Rankine is the natural absolute extension.
Frequently Asked Questions
What is 0°C in Rankine?
0°C = 491.67°R. This is the freezing point of water. In Fahrenheit terms: 32°F + 459.67 = 491.67°R.
Who still uses Rankine?
Rankine is used in US mechanical and chemical engineering, particularly in thermodynamics (Rankine cycle for steam power plants), HVAC, and aerospace. It rarely appears outside US engineering contexts. Internationally, kelvin is preferred.
What is the relationship between Rankine and Kelvin?
°R = K × 9/5. Both start at absolute zero, so the conversion is a simple scaling: Rankine degrees are 5/9 the size of kelvin degrees (same ratio as Fahrenheit to Celsius).
Is Rankine part of the SI system?
No. Rankine is part of the imperial/US engineering tradition. The SI absolute temperature unit is the kelvin. Rankine exists to serve the same purpose as kelvin but within the Fahrenheit framework.
Temperature conversion chart
| To Fahrenheit | To Celsius | To Kelvin | |
| From Fahrenheit (F) | F | (F - 32) × 5/9 | (F - 32) × 5/9 + 273.15 |
| From Celsius (C or o) | (C × 9/5) + 32 | C | C + 273.15 |
| From Kelvin (K) | (K - 273.15) × 9/5 + 32 | K - 273.15 | K |
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