Convert BTU per Pound-Rankine to Kilojoules per Kilogram-Kelvin
Instantly convert BTU per Pound-Rankine (BTU/(lb·°R)) to Kilojoules per Kilogram-Kelvin (kJ/(kg·K)) with our free online calculator.
Formula: BTU/(lb·°R) to kJ/(kg·K) — multiply by 4.1868
Reference Table
| BTU per Pound-Rankine (BTU/(lb·°R)) | Kilojoules per Kilogram-Kelvin (kJ/(kg·K)) |
|---|---|
| 1 | 4.1868 |
| 5 | 20.934 |
| 10 | 41.868 |
| 25 | 104.67 |
| 50 | 209.34 |
| 100 | 418.68 |
How to Convert BTU per Pound-Rankine to Kilojoules per Kilogram-Kelvin
Formula
To convert BTU per Pound-Rankine (BTU/(lb·°R)) to Kilojoules per Kilogram-Kelvin (kJ/(kg·K)): multiply by 4.1868
Step-by-Step
- Start with your value in BTU per Pound-Rankine (BTU/(lb·°R)).
- Multiply by 4.1868 to perform the conversion.
- The result is your value expressed in Kilojoules per Kilogram-Kelvin (kJ/(kg·K)).
Conversion Factor
1 BTU/(lb·°R) = 4.1868 kJ/(kg·K)
Reverse Factor
1 kJ/(kg·K) = 0.238846 BTU/(lb·°R)
Worked Example
Convert 25 BTU per Pound-Rankine to Kilojoules per Kilogram-Kelvin: 25 BTU/(lb·°R) = 104.67 kJ/(kg·K)
About BTU per Pound-Rankine (BTU/(lb·°R))
An imperial specific-entropy unit equal to approximately 4,186.8 J/(kg·K) — numerically very close to (and traditionally used as numerically interchangeable with) the kJ/(kg·K) value, since BTU/(lb·°R) and kJ/(kg·K) have a conversion factor of exactly 4.1868 / 4.184 ≈ 1.0007 (a coincidence of imperial unit definitions). BTU/(lb·°R) is the dominant unit in US-edition steam tables (Keenan-Keyes-Hill, NIST/ASME Steam Tables US-customary printing), US-edition thermodynamics textbooks (Cengel-Boles, Moran-Shapiro-Boettner US editions; Borgnakke-Sonntag), ASHRAE Handbook tables (refrigerant data through 2024 edition still dual-lists), and US petroleum/refining process design per API and GPSA Engineering Data Book. Reference values: saturated liquid water at 70°F: s_f ≈ 0.0746 BTU/(lb·°R); saturated steam at 14.7 psia (1 atm boiling point): s_g ≈ 1.7567 BTU/(lb·°R); the entropy of vaporization at 1 atm s_fg ≈ 1.4446 BTU/(lb·°R). Convert BTU/(lb·°R) to kJ/(kg·K) by multiplying by 4.1868; the near-unity conversion is why dual-unit thermodynamics textbooks need only one decimal of precision to map between systems.
About Kilojoule per Kilogram-Kelvin (kJ/(kg·K))
A metric specific-entropy unit equal to exactly 1,000 J/(kg·K). kJ/(kg·K) is the dominant working unit in international engineering steam tables per IAPWS-IF97, refrigerant property tables (Lemmon-Span-Wagner Helmholtz EoS for R-134a, R-410A, R-1234yf, R-744 CO₂, ammonia R-717), and gas-turbine working-fluid property charts per VDI 4670. Standard saturated water entropy at 100°C: s_f = 1.3069 kJ/(kg·K); saturated steam at same point: s_g = 7.3549 kJ/(kg·K); the entropy of vaporization s_fg = 6.0480 kJ/(kg·K) — a direct measure of phase-change reversible heat per unit mass at that temperature (s_fg · T = h_fg at saturation). T-s diagrams (temperature-entropy thermodynamic cycle plots used for Rankine, Brayton, refrigeration, organic Rankine ORC cycles) universally use kJ/(kg·K) on the horizontal axis. Mollier h-s diagrams for steam likewise use kJ/(kg·K). The unit is dominant in Cycle-Tempo, EBSILON, GateCycle, Thermoflex, IPSEpro power-plant simulators.
Quick Facts
- 1 BTU per Pound-Rankine equals 4.1868 Kilojoules per Kilogram-Kelvin
- 1 Kilojoule per Kilogram-Kelvin equals 0.238846 BTU per Pound-Rankine
- BTU per Pound-Rankine is a unit of specific entropy
- Kilojoule per Kilogram-Kelvin is a unit of specific entropy
- This conversion is commonly used in turbine design, refrigeration analysis, and power plant engineering
- The BTU per Pound-Rankine belongs to the imperial system
- The Kilojoule per Kilogram-Kelvin belongs to the metric system
Common BTU per Pound-Rankine to Kilojoule per Kilogram-Kelvin Conversions
| BTU per Pound-Rankine (BTU/(lb·°R)) | Kilojoules per Kilogram-Kelvin (kJ/(kg·K)) |
|---|---|
| 0.01 | 0.041868 |
| 0.1 | 0.41868 |
| 0.25 | 1.0467 |
| 0.5 | 2.0934 |
| 1 | 4.1868 |
| 2 | 8.3736 |
| 3 | 12.5604 |
| 5 | 20.934 |
| 10 | 41.868 |
| 15 | 62.802 |
| 20 | 83.736 |
| 25 | 104.67 |
| 50 | 209.34 |
| 75 | 314.01 |
| 100 | 418.68 |
| 250 | 1046.7 |
| 500 | 2093.4 |
| 1000 | 4186.8 |
| 5000 | 20934 |
| 10000 | 41868 |
Understanding BTU per Pound-Rankine
The BTU per Pound-Rankine (symbol: BTU/(lb·°R)) is a unit of specific entropy. An imperial specific-entropy unit equal to approximately 4,186.8 J/(kg·K) — numerically very close to (and traditionally used as numerically interchangeable with) the kJ/(kg·K) value, since BTU/(lb·°R) and kJ/(kg·K) have a conversion factor of exactly 4.1868 / 4.184 ≈ 1.0007 (a coincidence of imperial unit definitions). BTU/(lb·°R) is the dominant unit in US-edition steam tables (Keenan-Keyes-Hill, NIST/ASME Steam Tables US-customary printing), US-edition thermodynamics textbooks (Cengel-Boles, Moran-Shapiro-Boettner US editions; Borgnakke-Sonntag), ASHRAE Handbook tables (refrigerant data through 2024 edition still dual-lists), and US petroleum/refining process design per API and GPSA Engineering Data Book. Reference values: saturated liquid water at 70°F: s_f ≈ 0.0746 BTU/(lb·°R); saturated steam at 14.7 psia (1 atm boiling point): s_g ≈ 1.7567 BTU/(lb·°R); the entropy of vaporization at 1 atm s_fg ≈ 1.4446 BTU/(lb·°R). Convert BTU/(lb·°R) to kJ/(kg·K) by multiplying by 4.1868; the near-unity conversion is why dual-unit thermodynamics textbooks need only one decimal of precision to map between systems.
It belongs to the imperial measurement system.
BTU per Pound-Rankine are commonly used in turbine design, refrigeration analysis, and power plant engineering.
Understanding Kilojoules per Kilogram-Kelvin
The Kilojoule per Kilogram-Kelvin (symbol: kJ/(kg·K)) is a unit of specific entropy. A metric specific-entropy unit equal to exactly 1,000 J/(kg·K). kJ/(kg·K) is the dominant working unit in international engineering steam tables per IAPWS-IF97, refrigerant property tables (Lemmon-Span-Wagner Helmholtz EoS for R-134a, R-410A, R-1234yf, R-744 CO₂, ammonia R-717), and gas-turbine working-fluid property charts per VDI 4670. Standard saturated water entropy at 100°C: s_f = 1.3069 kJ/(kg·K); saturated steam at same point: s_g = 7.3549 kJ/(kg·K); the entropy of vaporization s_fg = 6.0480 kJ/(kg·K) — a direct measure of phase-change reversible heat per unit mass at that temperature (s_fg · T = h_fg at saturation). T-s diagrams (temperature-entropy thermodynamic cycle plots used for Rankine, Brayton, refrigeration, organic Rankine ORC cycles) universally use kJ/(kg·K) on the horizontal axis. Mollier h-s diagrams for steam likewise use kJ/(kg·K). The unit is dominant in Cycle-Tempo, EBSILON, GateCycle, Thermoflex, IPSEpro power-plant simulators.
It belongs to the metric measurement system.
Kilojoules per Kilogram-Kelvin are commonly used in turbine design, refrigeration analysis, and power plant engineering.
Why Convert BTU per Pound-Rankine to Kilojoules per Kilogram-Kelvin?
Converting between BTU per Pound-Rankine and Kilojoules per Kilogram-Kelvin is a frequent requirement for engineers, scientists, and students working with specific 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 specific entropy conversion is essential.
Frequently Asked Questions
How do I convert BTU per Pound-Rankine to Kilojoules per Kilogram-Kelvin?
An imperial specific-entropy unit equal to approximately 4,186. To convert BTU per Pound-Rankine to Kilojoules per Kilogram-Kelvin, multiply by 4.1868. For example, 25 BTU/(lb·°R) equals 104.67 kJ/(kg·K).
How many Kilojoules per Kilogram-Kelvin are in 1 BTU per Pound-Rankine?
There are 4.1868 Kilojoules per Kilogram-Kelvin in 1 BTU per Pound-Rankine.
How many BTU per Pound-Rankine are in 1 Kilojoule per Kilogram-Kelvin?
There are 0.238846 BTU per Pound-Rankine in 1 Kilojoule per Kilogram-Kelvin.
What is the formula for BTU per Pound-Rankine to Kilojoule per Kilogram-Kelvin conversion?
The formula is: multiply by 4.1868. This means 1 BTU/(lb·°R) = 4.1868 kJ/(kg·K).
Is a BTU per Pound-Rankine bigger than a Kilojoule per Kilogram-Kelvin?
No. One BTU per Pound-Rankine is smaller than one Kilojoule per Kilogram-Kelvin because 1 BTU/(lb·°R) equals 4.1868 kJ/(kg·K), which is greater than 1.
When do you need to convert between BTU per Pound-Rankine and Kilojoules per Kilogram-Kelvin?
A metric specific-entropy unit equal to exactly 1,000 J/(kg·K). BTU per Pound-Rankine and Kilojoule per Kilogram-Kelvin are both specific 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.