Heat Conversion Chart
Quick-reference heat conversion chart. The tables below compare the most common units side by side. Download the free PDF for offline and printable use.
Standards and method
Values are calculated from the shared conversion-factor library. Exact defined relationships are preserved; displayed results are rounded only for readability.
Maintained by Miguel Coelho. Updated . See our editorial policy.
Printable heat conversion chart
Heating and cooling capacity, heat energy and temperature scales. Includes the exact definition, formulas, a worked example and sources. Conversion values are checked against the defining constants, and reference data is cited to its source, before the PDF is published.
Free to print, share and use in teaching materials with attribution (CC BY 4.0).
Heat Conversion Table
Heat energy
| Unit | per 1 J |
|---|---|
| Joule (J) | 1 J |
| Kilojoule (kJ) | 0.001 kJ |
| Kilocalorie (kcal) | 0.000239006 kcal |
| Watt Hour (Wh) | 0.000277778 Wh |
| Kilowatt Hour (kWh) | 2.7778e-7 kWh |
| British Thermal Unit (BTU) | 0.000947817 BTU |
| Therm (thm) | 9.4782e-9 thm |
Heating and cooling capacity
| Unit | per 1 W |
|---|---|
| Watt (W) | 1 W |
| Kilowatt (kW) | 0.001 kW |
| BTU per Hour (BTU/h) | 3.41214 BTU/h |
| Ton of Refrigeration (RT) | 0.000284345 RT |
Values are calculated from the shared conversion-factor library. Exact defined relationships are preserved; displayed results are rounded only for readability.
Full heat conversion chart
Heating and cooling capacity, heat energy and temperature scales. These are the same tables as the printable PDF. For: HVAC engineers, installers, energy auditors and students.
- Exact definition
- 1 BTU/h = 0.293 071 W; 1 RT = 12,000 BTU/h; 1 therm = 100,000 BTU
- Formula
- kW = BTU/h × 0.000 293 071
- Reverse
- BTU/h = kW × 3,412.14
- Worked example
- A 24,000 BTU/h heat pump = 7.03 kW = 2 RT
- Rounding
- Capacities are rounded as shown. Rankine = (°C + 273.15) × 1.8.
Conversion factor matrix
Read across: 1 unit in the left column equals the value shown in each column unit.
| 1 unit = | J | kJ | kcal | Wh | kWh | BTU | thm |
|---|---|---|---|---|---|---|---|
| 1 J | 1 | 0.001 | 2.39006 × 10⁻⁴ | 2.77778 × 10⁻⁴ | 2.77778 × 10⁻⁷ | 9.47817 × 10⁻⁴ | 9.47817 × 10⁻⁹ |
| 1 kJ | 1,000 | 1 | 0.239006 | 0.277778 | 2.77778 × 10⁻⁴ | 0.947817 | 9.47817 × 10⁻⁶ |
| 1 kcal | 4,184 | 4.184 | 1 | 1.16222 | 0.00116222 | 3.96567 | 3.96567 × 10⁻⁵ |
| 1 Wh | 3,600 | 3.6 | 0.860421 | 1 | 0.001 | 3.41214 | 3.41214 × 10⁻⁵ |
| 1 kWh | 3.6 × 10⁶ | 3,600 | 860.421 | 1,000 | 1 | 3,412.14 | 0.0341214 |
| 1 BTU | 1,055.06 | 1.05506 | 0.252164 | 0.293071 | 2.93071 × 10⁻⁴ | 1 | 1 × 10⁻⁵ |
| 1 thm | 1.05506 × 10⁸ | 105,506 | 25,216.4 | 29,307.1 | 29.3071 | 100,000 | 1 |
Air-conditioner and heat-pump sizes: BTU/h to kW
| BTU per hour (BTU/h) | Kilowatts (kW) | Tons of refrigeration (RT) |
|---|---|---|
| 5,000 | 1.47 | 0.42 |
| 6,000 | 1.76 | 0.50 |
| 7,000 | 2.05 | 0.58 |
| 8,000 | 2.34 | 0.67 |
| 9,000 | 2.64 | 0.75 |
| 10,000 | 2.93 | 0.83 |
| 12,000 | 3.52 | 1.00 |
| 14,000 | 4.10 | 1.17 |
| 15,000 | 4.40 | 1.25 |
| BTU per hour (BTU/h) | Kilowatts (kW) | Tons of refrigeration (RT) |
|---|---|---|
| 18,000 | 5.28 | 1.50 |
| 21,000 | 6.15 | 1.75 |
| 24,000 | 7.03 | 2.00 |
| 30,000 | 8.79 | 2.50 |
| 36,000 | 10.55 | 3.00 |
| 42,000 | 12.31 | 3.50 |
| 48,000 | 14.07 | 4.00 |
| 60,000 | 17.58 | 5.00 |
Kilowatts to BTU/h (boilers, heaters)
| Kilowatts (kW) | BTU per hour (BTU/h) |
|---|---|
| 1 | 3,412 |
| 2 | 6,824 |
| 3 | 10,236 |
| 4 | 13,649 |
| 5 | 17,061 |
| 6 | 20,473 |
| 7 | 23,885 |
| 8 | 27,297 |
| 9 | 30,709 |
| 10 | 34,121 |
| 11 | 37,534 |
| Kilowatts (kW) | BTU per hour (BTU/h) |
|---|---|
| 12 | 40,946 |
| 13 | 44,358 |
| 14 | 47,770 |
| 15 | 51,182 |
| 16 | 54,594 |
| 17 | 58,006 |
| 18 | 61,419 |
| 19 | 64,831 |
| 20 | 68,243 |
| 21 | 71,655 |
| 22 | 75,067 |
| Kilowatts (kW) | BTU per hour (BTU/h) |
|---|---|
| 23 | 78,479 |
| 24 | 81,891 |
| 25 | 85,304 |
| 26 | 88,716 |
| 27 | 92,128 |
| 28 | 95,540 |
| 29 | 98,952 |
| 30 | 102,364 |
| 35 | 119,425 |
| 40 | 136,486 |
| 50 | 170,607 |
Temperature scales including Rankine
| Celsius (°C) | Fahrenheit (°F) | Kelvin (K) | Rankine (°R) |
|---|---|---|---|
| −273.15 | −459.67 | 0 | 0 |
| −40 | −40 | 233.15 | 419.67 |
| 0 | 32 | 273.15 | 491.67 |
| 20 | 68 | 293.15 | 527.67 |
| 37 | 98.6 | 310.15 | 558.27 |
| 100 | 212 | 373.15 | 671.67 |
| 200 | 392 | 473.15 | 851.67 |
| 300 | 572 | 573.15 | 1,031.67 |
| 500 | 932 | 773.15 | 1,391.67 |
| 1,000 | 1,832 | 1,273.15 | 2,291.67 |
Sources for this chart
Conversion values on this sheet are generated by the AllUnitConversions conversion library and automatically checked against the exact definitions above before the PDF is produced; reference tables are taken from the sources listed.
- NIST Special Publication 811 — Guide for the Use of the International System of Units
- BIPM SI Brochure, 9th edition — Definitions of the SI units, including the kelvin
Related Converters & Charts
Heat Conversion Chart FAQs
Common questions about the heat conversion chart.
What does this heat conversion chart include?
It lists the most common heat units side by side with their conversion factors, plus a free printable PDF you can download for offline reference.
What exact definition is this heat chart based on?
1 BTU/h = 0.293 071 W; 1 RT = 12,000 BTU/h; 1 therm = 100,000 BTU. Formula: kW = BTU/h × 0.000 293 071. Capacities are rounded as shown. Rankine = (°C + 273.15) × 1.8.
Can I download this chart as a PDF, CSV, or JSON?
Yes. Use the Download A4 PDF or US Letter PDF buttons for a printable version, or download the same tables as CSV or JSON from the links on this page.