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BTU/hour to watt: exact 0.293 factor, HVAC and heater examples, conversion chart, and practical tips
Conversion formula
Verification: factors follow standard unit definitions; round for display only.
Quick reference chart
| BTU/hour | Watt |
|---|---|
| 1 | 0.293071 |
| 2 | 0.586142 |
| 3 | 0.879213 |
| 4 | 1.172284 |
| 5 | 1.465355 |
| 6 | 1.758426 |
Educational explanation
BTU/hour to watt
Convert BTU/h to W when a US window-AC brochure, gas-furnace comparison, or HVAC quote lists BTU per hour but your electric panel schedule, SI engineering sheet, or utility demand model expects watts.
BTU per hour (BTU/h) is a customary US rate tied to the British thermal unit. The watt (W) is the SI unit of power. This catalog defines 1 BTU/h = 0.293071070172 W, so:
W = BTU/h × 0.293071070172 · equivalently W = BTU/h ÷ 3.412141633
HVAC shoppers often memorize 1 kW ≈ 3,412 BTU/h in the reverse direction. For BTU/h → W, divide by 3.412 or multiply by 0.293071070172—the calculator uses the full catalog constant.
Step-by-step conversion (worked example)
Convert 12,000 BTU/h to watts—a common window AC cooling rating:
- Write the formula: W = BTU/h × 0.293071070172
- Multiply: 12,000 × 0.293071070172 = 3,516.9 W
- Round for display: 3.52 kW on a panel schedule
Second worked example (5,000 BTU/h mini unit)
- 5,000 × 0.293071070172 = 1,465.4 W
- Round: 1.47 kW circuit sizing starting point
Quick mental estimate (no calculator)
Multiply BTU/h by 0.29 (or divide by 3.4). Example: 10,000 BTU/h → about 2,900 W (exact: 2,931 W). The 0.29 shortcut runs ~1% low—fine for comparing two room AC units.
BTU/hour to watt conversion chart
| BTU/hour | Watts (W) | Kilowatts (kW) | Typical context |
|---|---|---|---|
| 3,412 BTU/h | 1,000 W | 1 kW | Definition anchor (inverse of 1 kW rule) |
| 5,000 BTU/h | 1,465 W | 1.47 kW | Small window / portable AC |
| 9,000 BTU/h | 2,638 W | 2.64 kW | Bedroom mini-split class |
| 12,000 BTU/h | 3,517 W | 3.52 kW | 1-ton cooling (HVAC shorthand) |
| 18,000 BTU/h | 5,275 W | 5.28 kW | 1.5-ton mini-split |
| 24,000 BTU/h | 7,034 W | 7.03 kW | 2-ton residential unit |
| 36,000 BTU/h | 10,551 W | 10.6 kW | 3-ton light commercial |
Where BTU/h → W comes up
- Window AC shopping: Cooling capacity in BTU/h; breaker sizing in watts.
- Electric vs gas heat comparison: Gas input in BTU/h; electric element in kW.
- Load calculations: Sum circuits in watts after converting each BTU/h rating.
Watt to BTU/hour
Convert W to BTU/h when an electric heater nameplate or SI spec lists watts but a US HVAC quote or gas-furnace comparison expects BTU per hour.
BTU/h = W × 3.412141633130529 · equivalently BTU/h = W ÷ 0.293071070172
Step-by-step conversion (worked example)
Convert 1,500 W portable heater to BTU/h:
- 1,500 × 3.412141633 = 5,118.2 BTU/h
Quick reference (W → BTU/h)
| Watts (W) | BTU/hour | Typical context |
|---|---|---|
| 1,000 W | 3,412 BTU/h | 1 kW rule anchor |
| 1,500 W | 5,118 BTU/h | Portable room heater |
| 3,500 W | 11,943 BTU/h | ≈ small window AC band |
See also watts to BTU/hour for extended reverse-direction copy.
Cooling vs heating BTU/h, efficiency, and related tools
Rated BTU/h is capacity, not always electrical draw. Apply COP/EER or manufacturer amp data for circuit sizing.
Common mistakes to avoid
- Equating cooling BTU/h with electrical watts one-to-one—AC units draw less than cooling BTU/h divided by 3.412 because of COP/EER.
- Using 3.412 as BTU/h per watt for cooling nameplate—that shortcut maps thermal power to electric input only at COP = 1.
- Mixing BTU (energy) with BTU/h (power)—hours matter for energy, not for rate.
Related converters
watts to BTU/hour, watts to kilowatts, horsepower to kilowatts, and watts to megawatts.
Frequently asked questions
What is the formula to convert BTU/hour to watts?
W = BTU/h × 0.293071070172. Example: 12,000 BTU/h = 3,516.9 W.
What is the formula to convert watts to BTU/hour?
BTU/h = W × 3.412141633. Example: 1,000 W = 3,412 BTU/h.
How many watts are in 1 BTU/hour?
Exactly 0.293071070172 W on this site's catalog.
How many watts is a 12,000 BTU/h air conditioner?
12,000 × 0.293071070172 = 3,516.9 W thermal rating—not necessarily the electrical plug draw. Check the nameplate amps.
What is 5,000 BTU/h in watts?
1,465.4 W (≈ 1.47 kW) on the thermal rating scale.
Why do HVAC guides say 1 kW = 3,412 BTU/h?
That is the inverse of 0.293071070172 W per BTU/h—the same catalog anchor used here.
Is BTU/h to watt exact?
Yes for the unit definition wired into converters.js. Equipment efficiency is a separate question.
Can I size a breaker using BTU/h ÷ 3.412?
Only as a rough upper bound for resistive heat. Air conditioners need manufacturer amp/Voltage data or COP/EER.
What is the difference between BTU and BTU/h?
BTU is energy. BTU/h is power (energy per hour). This page converts the rate unit BTU/h.
How do I validate a spreadsheet?
Convert 12,000 BTU/h → 3,516.9 W → 12,000 BTU/h round-trip using the catalog factors.
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