BTU / Watts / kW Conversion Chart
The heat-rate conversions between the imperial and metric sides of the trade: 1 kW = 3,412 BTU/hr, tabulated at the capacities on real nameplates — 5,000 BTU/hr window units to 120,000 BTU/hr light commercial — and back from the common electric-heat kW sizes. Exact derivations, not rounded rules of thumb.
BTU/hr → kW / Watts / Tons
| BTU/hr | kW | Watts | Tons |
|---|---|---|---|
| 5,000 | 1.47 | 1,465 | 0.42 |
| 6,000 | 1.76 | 1,758 | 0.5 |
| 9,000 | 2.64 | 2,638 | 0.75 |
| 12,000 | 3.52 | 3,517 | 1 |
| 18,000 | 5.28 | 5,275 | 1.5 |
| 24,000 | 7.03 | 7,034 | 2 |
| 30,000 | 8.79 | 8,792 | 2.5 |
| 36,000 | 10.55 | 10,551 | 3 |
| 42,000 | 12.31 | 12,309 | 3.5 |
| 48,000 | 14.07 | 14,067 | 4 |
| 60,000 | 17.58 | 17,584 | 5 |
| 72,000 | 21.1 | 21,101 | 6 |
| 90,000 | 26.38 | 26,376 | 7.5 |
| 120,000 | 35.17 | 35,169 | 10 |
kW → BTU/hr (electric heat sizes)
| kW | BTU/hr | Tons equivalent |
|---|---|---|
| 1 | 3,412 | 0.28 |
| 1.5 | 5,118 | 0.43 |
| 2 | 6,824 | 0.57 |
| 3 | 10,236 | 0.85 |
| 5 | 17,061 | 1.42 |
| 7.5 | 25,591 | 2.13 |
| 10 | 34,121 | 2.84 |
| 15 | 51,182 | 4.27 |
| 20 | 68,243 | 5.69 |
| 25 | 85,304 | 7.11 |
| 30 | 102,364 | 8.53 |
The identities behind the table
Everything above derives from one pinned definition: the international-table BTU of 1,055.05585262 joules. Divide by 3,600 seconds and 1 BTU/hr is 0.2931 watts; invert and 1 kW is 3,412 BTU/hr. A ton of refrigeration (12,000 BTU/hr by definition) is 3,517 watts, one mechanical horsepower delivers 2,544 BTU/hr, and a therm of gas (100,000 BTU) holds 29.3 kWh of energy.
Size the load itself with the BTU load calculator or the cooling tonnage calculator, and move between tonnage and airflow with the BTU / tonnage / CFM chart.
Common questions
How many BTU per hour is 1 kW?
One kilowatt equals 3,412 BTU per hour (3,412.14 exactly, from the international-table BTU of 1,055.056 joules). The relationship is a unit definition, not a rule of thumb — a 10 kW electric heat strip always delivers 34,121 BTU/hr.
How many watts is 12,000 BTU?
A rate of 12,000 BTU/hr — one ton of cooling — equals about 3,517 watts of heat moved. Note that this is the thermal rate, not the electrical draw: an air conditioner moves far more heat than the electricity it consumes, which is what EER and COP measure.
Why does a heat pump deliver more BTU than its wattage suggests?
Electric resistance heat converts electricity to heat one-for-one: 1 kW in, 3,412 BTU/hr out, always. A heat pump instead moves heat from outside, so 1 kW of input can deliver 8,000–12,000 BTU/hr depending on conditions — a COP of 2.5 to 3.5. That multiplier is why the same table serves both: read resistance heat directly, and multiply by COP for a heat pump.