Convert Units
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Overview
Power and heat-flow rate units span from the SI watt, to BTU per hour (HVAC), various horsepower definitions (mechanical, electric, metric), refrigeration tons, and physics-industry composites like atmosphere-flow metrics (atm·cm³/min). This converter lets you pivot through all of them instantly.
Formula & Methodology
We use watts (W) as the pivot:
$$ P_{W} = P_{\rm in} \times f_{\rm from}, \quad P_{\rm out} = \frac{P_{W}}{f_{\rm to}} $$
| Unit | Symbol | →W | Note |
|---|---|---|---|
| Watt | W | 1 | SI power |
| BTU/hour | BTU/h | 0.293071 | HVAC |
| Horsepower (mech) | hp | 745.7 | 550 ft·lbf/s |
| Ton refrigeration (IT) | ton_Ref | 3516.85 | US thermic |
| atm·cm³/min | atm·ccm | 1.68875×10⁻³ | 1 atm×1 cm³/min |
| atm·cm³/s | atm·ccs | 0.101325 | …/s |
| atm·ft³/h | atm·cfh | 0.797001 | …/h |
| atm·ft³/min | atm·cfm | 47.82007 | …/min |
| atm·ft³/s | atm·cfs | 2869.204 | …/s |
| BTUIT/s | BTU_it_s | 1055.056 | BTU per sec |
| calIT/s | cal_s | 4.1868 | food calorie/sec |
| erg/s | erg_s | 1×10⁻⁷ | CGS |
| ft·lbf/s | ftlbf_s | 1.3558 | mech |
| ft·lbf/h | ftlbf_h | 3.766×10⁻⁴ | …/h |
| ft·lbf/min | ftlbf_min | 0.022597 | …/min |
| hp (electric) | hp_elec | 746 | IEC |
| hp (metric) | hp_metric | 735.5 | 75 m·kgf/s |
| W·h | W_h | 3600 | energy unit |
Examples
- 5 kW → BTU/h: 5×3412.14 ≈ 17060.7 BTU/h
- 100 hp → W: 100×745.7 ≈ 74 570 W
- 10 atm·ft³/min → kW: 10×47.82007 ≈ 478.2 W
Frequently Asked Questions
Why pivot through watts?
Watt is the SI base unit for power; all other units convert to/from it for consistency.
What is “ton refrigeration”?
One “ton” is the rate of heat removal to melt one ton of ice in 24 h (≈3.516 kW).
How accurate are these conversions?
All factors are drawn from industry/ISO standards; slight variation may occur in legacy definitions.