BTU to Watts Converter
Convert BTU per hour to watts and watts to BTU/hr. Used for electric heater sizing, AC power requirements, and electrical load calculations.
1 Watt = 3.412 BTU/hr | 1 BTU/hr = 0.293 Watts
BTU/hr ↔ Watts Calculator
Quick conversions:
BTU to Watts Conversion Table
| BTU/hr | Watts | kW | Typical Device |
|---|---|---|---|
| 1,000 | 293 | 0.29 | Small space heater |
| 3,412 | 1000 | 1.00 | 1 kW electric heater |
| 5,000 | 1465 | 1.47 | Window AC unit (small) |
| 5,118 | 1500 | 1.50 | 1,500W space heater |
| 8,000 | 2345 | 2.34 | Window AC unit (medium) |
| 10,000 | 2931 | 2.93 | Large window AC |
| 12,000 | 3517 | 3.52 | 1-ton AC / mini-split |
| 18,000 | 5275 | 5.28 | 1.5-ton AC system |
| 24,000 | 7034 | 7.03 | 2-ton AC system |
| 36,000 | 10551 | 10.55 | 3-ton AC system |
| 48,000 | 14067 | 14.07 | 4-ton AC system |
| 60,000 | 17584 | 17.58 | 5-ton AC system |
Watts to BTU — Common Electric Heater Sizes
| Heater Watts | BTU/hr Output | Heats Up To |
|---|---|---|
| 500W | 1706 | 50-100 sq ft |
| 750W | 2559 | 75-150 sq ft |
| 1,000W | 3412 | 100-200 sq ft |
| 1,500W | 5118 | 150-300 sq ft |
| 2,000W | 6824 | 200-400 sq ft |
| 3,000W | 10236 | 300-500 sq ft |
| 4,000W | 13649 | 400-600 sq ft |
| 5,000W | 17061 | 500-750 sq ft |
BTU to Watts Conversion Formula
BTU/hr to Watts
Watts = BTU/hr ÷ 3.412
Example: 5,000 BTU/hr ÷ 3.412 = 1,465 watts
Watts to BTU/hr
BTU/hr = Watts × 3.412
Example: 1,500W × 3.412 = 5,118 BTU/hr
Frequently Asked Questions
How many BTU is a 1,500 watt heater?
A 1,500 watt space heater produces 5,118 BTU/hr (1,500 × 3.412). This is the most common portable electric heater size and can heat a room of about 150-300 square feet.
How many watts is 5,000 BTU?
5,000 BTU/hr equals approximately 1,465 watts. A 5,000 BTU window AC draws about 1,465W running — roughly the same as a standard space heater on a 15-amp household circuit.
How many watts does a 12,000 BTU AC use?
A 12,000 BTU AC uses approximately 3,517 watts (3.5 kW) at full capacity. However, actual power draw depends on the unit's efficiency (EER/SEER rating). A high-efficiency unit with 12 EER uses only 1,000 watts: 12,000 BTU ÷ 12 EER = 1,000W.
What size breaker do I need for a BTU-rated heater?
Convert BTU/hr to watts (divide by 3.412), then divide by voltage (120V or 240V) to get amps. Size the breaker at 125% of continuous load. Example: 10,000 BTU heater = 2,931W ÷ 240V = 12.2A × 1.25 = 15.3A — use a 20-amp breaker.
What size generator do I need for a BTU-rated AC?
Convert BTU to watts, then add 50-70% for startup surge. A 12,000 BTU AC = ~3,500W running + ~2,000W surge = 5,500W minimum. A 6,500W generator provides adequate margin. For multiple units, add the running watts together plus one unit's surge.
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