Convert BTU per Rankine to Joules per Kelvin
Instantly convert BTU per Rankine (BTU/°R) to Joules per Kelvin (J/K) with our free online calculator.
Formula: BTU/°R to J/K — multiply by 1899.11
Reference Table
| BTU per Rankine (BTU/°R) | Joules per Kelvin (J/K) |
|---|---|
| 1 | 1899.11 |
| 5 | 9495.55 |
| 10 | 18991.1 |
| 25 | 47477.8 |
| 50 | 94955.5 |
| 100 | 189911 |
How to Convert BTU per Rankine to Joules per Kelvin
Formula
To convert BTU per Rankine (BTU/°R) to Joules per Kelvin (J/K): multiply by 1899.11
Step-by-Step
- Start with your value in BTU per Rankine (BTU/°R).
- Multiply by 1899.11 to perform the conversion.
- The result is your value expressed in Joules per Kelvin (J/K).
Conversion Factor
1 BTU/°R = 1899.11 J/K
Reverse Factor
1 J/K = 0.000526562 BTU/°R
Worked Example
Convert 25 BTU per Rankine to Joules per Kelvin: 25 BTU/°R = 47477.8 J/K
About BTU per Rankine (BTU/°R)
An imperial entropy unit equal to approximately 1,899.11 J/K (1 BTU = 1,055.06 J, 1 °R = 5/9 K, ratio = 1,899.11). BTU/°R is the working unit of US-edition steam-table absolute entropy values (Keenan-Keyes-Hill steam tables, NIST/ASME Steam Tables published in BTU units), US refrigeration-cycle design per ASHRAE Handbook chapters 1-2 (Fundamentals + Refrigeration tables), and US-edition gas-cycle thermodynamics textbooks (Cengel-Boles, Moran-Shapiro both still publish dual-unit editions). Standard reference values: saturated liquid water at 70°F has absolute specific entropy s_f ≈ 0.0746 BTU/(lb·°R); saturated steam at 212°F (1 atm) has s_g ≈ 1.7567 BTU/(lb·°R) — the entropy gain of vaporization. Total entropy flows in US power-plant heat balances are sometimes reported in BTU/(°R·hr) or BTU/(°R·s). For a large industrial process like a 600 MW(e) coal-fired Rankine cycle, total entropy rejection rate ≈ 5 × 10⁶ BTU/(°R·hr). Convert BTU/°R to J/K by multiplying by 1899.11; to kJ/K by multiplying by 1.899.
About Joule per Kelvin (J/K)
The SI unit of entropy per ISO 80000-5 §5-19 — the thermodynamic state function that measures the spread of energy among accessible microstates (Boltzmann formulation S = k_B · ln Ω) or, equivalently, heat absorbed per unit temperature in reversible processes (Clausius formulation dS = δQ_rev/T). J/K is the universal unit for entropy across statistical mechanics (Gibbs, Helmholtz, Boltzmann formulations), classical thermodynamics, and the analogous information-theory definition (Shannon entropy in bits relates through the conversion 1 bit = k_B · ln 2 = 9.57 × 10⁻²⁴ J/K). The second law of thermodynamics (ΔS_universe ≥ 0 for spontaneous processes) and the third law (S → 0 as T → 0 for perfect crystals per Nernst) are both formalized in J/K. Reference values per NIST-JANAF Thermochemical Tables: standard molar entropy of liquid water at 298.15 K is 69.95 J/(mol·K); gaseous CO₂ at standard conditions is 213.79 J/(mol·K); diamond is 2.377 J/(mol·K) (very low — highly ordered crystal); graphite is 5.74 J/(mol·K). Boltzmann's constant k_B = 1.380649 × 10⁻²³ J/K (exact since 2019 SI revision).
Quick Facts
- 1 BTU per Rankine equals 1899.11 Joules per Kelvin
- 1 Joule per Kelvin equals 0.000526562 BTU per Rankine
- BTU per Rankine is a unit of entropy
- Joule per Kelvin is a unit of entropy
- This conversion is commonly used in thermodynamics, refrigeration cycles, and chemical engineering
- The BTU per Rankine belongs to the imperial system
- The Joule per Kelvin belongs to the metric system
Common BTU per Rankine to Joule per Kelvin Conversions
| BTU per Rankine (BTU/°R) | Joules per Kelvin (J/K) |
|---|---|
| 0.01 | 18.9911 |
| 0.1 | 189.911 |
| 0.25 | 474.777 |
| 0.5 | 949.555 |
| 1 | 1899.11 |
| 2 | 3798.22 |
| 3 | 5697.33 |
| 5 | 9495.55 |
| 10 | 18991.1 |
| 15 | 28486.6 |
| 20 | 37982.2 |
| 25 | 47477.8 |
| 50 | 94955.5 |
| 75 | 142433 |
| 100 | 189911 |
| 250 | 474778 |
| 500 | 949555 |
| 1000 | 1899110 |
| 5000 | 9495550 |
| 10000 | 18991100 |
Understanding BTU per Rankine
The BTU per Rankine (symbol: BTU/°R) is a unit of entropy. An imperial entropy unit equal to approximately 1,899.11 J/K (1 BTU = 1,055.06 J, 1 °R = 5/9 K, ratio = 1,899.11). BTU/°R is the working unit of US-edition steam-table absolute entropy values (Keenan-Keyes-Hill steam tables, NIST/ASME Steam Tables published in BTU units), US refrigeration-cycle design per ASHRAE Handbook chapters 1-2 (Fundamentals + Refrigeration tables), and US-edition gas-cycle thermodynamics textbooks (Cengel-Boles, Moran-Shapiro both still publish dual-unit editions). Standard reference values: saturated liquid water at 70°F has absolute specific entropy s_f ≈ 0.0746 BTU/(lb·°R); saturated steam at 212°F (1 atm) has s_g ≈ 1.7567 BTU/(lb·°R) — the entropy gain of vaporization. Total entropy flows in US power-plant heat balances are sometimes reported in BTU/(°R·hr) or BTU/(°R·s). For a large industrial process like a 600 MW(e) coal-fired Rankine cycle, total entropy rejection rate ≈ 5 × 10⁶ BTU/(°R·hr). Convert BTU/°R to J/K by multiplying by 1899.11; to kJ/K by multiplying by 1.899.
It belongs to the imperial measurement system.
BTU per Rankine are commonly used in thermodynamics, refrigeration cycles, and chemical engineering.
Understanding Joules per Kelvin
The Joule per Kelvin (symbol: J/K) is a unit of entropy. The SI unit of entropy per ISO 80000-5 §5-19 — the thermodynamic state function that measures the spread of energy among accessible microstates (Boltzmann formulation S = k_B · ln Ω) or, equivalently, heat absorbed per unit temperature in reversible processes (Clausius formulation dS = δQ_rev/T). J/K is the universal unit for entropy across statistical mechanics (Gibbs, Helmholtz, Boltzmann formulations), classical thermodynamics, and the analogous information-theory definition (Shannon entropy in bits relates through the conversion 1 bit = k_B · ln 2 = 9.57 × 10⁻²⁴ J/K). The second law of thermodynamics (ΔS_universe ≥ 0 for spontaneous processes) and the third law (S → 0 as T → 0 for perfect crystals per Nernst) are both formalized in J/K. Reference values per NIST-JANAF Thermochemical Tables: standard molar entropy of liquid water at 298.15 K is 69.95 J/(mol·K); gaseous CO₂ at standard conditions is 213.79 J/(mol·K); diamond is 2.377 J/(mol·K) (very low — highly ordered crystal); graphite is 5.74 J/(mol·K). Boltzmann's constant k_B = 1.380649 × 10⁻²³ J/K (exact since 2019 SI revision).
It belongs to the metric measurement system.
Joules per Kelvin are commonly used in thermodynamics, refrigeration cycles, and chemical engineering.
Why Convert BTU per Rankine to Joules per Kelvin?
Converting between BTU per Rankine and Joules per Kelvin is a frequent requirement for engineers, scientists, and students working with entropy values. Different industries and regions favour different unit systems, so having a dependable conversion tool saves time and prevents errors in technical calculations. Whether you are verifying a specification sheet, cross-checking simulation results, or preparing a report for an international audience, accurate entropy conversion is essential.
Frequently Asked Questions
How do I convert BTU per Rankine to Joules per Kelvin?
An imperial entropy unit equal to approximately 1,899. To convert BTU per Rankine to Joules per Kelvin, multiply by 1899.11. For example, 25 BTU/°R equals 47477.8 J/K.
How many Joules per Kelvin are in 1 BTU per Rankine?
There are 1899.11 Joules per Kelvin in 1 BTU per Rankine.
How many BTU per Rankine are in 1 Joule per Kelvin?
There are 0.000526562 BTU per Rankine in 1 Joule per Kelvin.
What is the formula for BTU per Rankine to Joule per Kelvin conversion?
The formula is: multiply by 1899.11. This means 1 BTU/°R = 1899.11 J/K.
Is a BTU per Rankine bigger than a Joule per Kelvin?
No. One BTU per Rankine is smaller than one Joule per Kelvin because 1 BTU/°R equals 1899.11 J/K, which is greater than 1.
When do you need to convert between BTU per Rankine and Joules per Kelvin?
The SI unit of entropy per ISO 80000-5 §5-19 — the thermodynamic state function that measures the spread of energy among accessible microstates (Boltzmann formulation S = k_B · ln Ω) or, equivalently, heat absorbed per u... BTU per Rankine and Joule per Kelvin are both entropy units, so conversion comes up whenever one source of information uses one unit and another uses the other — a classic cross-reference challenge in engineering, trade, travel, and everyday life.