Convert BTU per Hour to Milliwatts
1 BTU per hour (BTU/h) equals 293.0710702 milliwatts (mW).
1 BTU/h = 293.0710702 mW
Type in either box. Scientific notation works: 1.5e-3.
Converting a list? Use the bulk BTU per hour to milliwatt converter to paste a column from Excel.
How to Convert BTU per Hour to Milliwatt
- 1 BTU/h = 293.0710702 mW
- 1 mW = 0.003412141633 BTU/h
- Example: convert 15 BTU/h to mW: 15 BTU/h = 15 × 293.0710702 mW = 4396.066053 mW
Formula
mW = BTU/h × 293.0710701722
Derivation from SI units:
- 1 BTU/h = 1055.05585262 J ÷ 3600 s = 0.29307107 W
- 1 mW = 10⁻³ W
- 1 BTU/h = 0.2930710701722 W ÷ 0.001 W per mW = 293.0710701722 mW
Both units are defined exactly, so the factor is exact. BTU per Hour definition: BTU per hour; Milliwatt definition: milliwatt.
Worked examples
- A reading of 9000 BTU/h converts to 2637639.632 mW.
9000 BTU/h × 293.0710702 = 2637639.632 mW - A value of 36000 BTU/h is 10550558.53 mW.
36000 BTU/h × 293.0710702 = 10550558.53 mW
BTU per Hour to Milliwatt conversion table
| BTU per Hour (BTU/h) | Milliwatts (mW) |
|---|---|
| 1000 BTU/h | 293071.0702 mW |
| 3412 BTU/h | 999958.4914 mW |
| 5000 BTU/h | 1465355.351 mW |
| 6000 BTU/h | 1758426.421 mW |
| 8000 BTU/h | 2344568.561 mW |
| 9000 BTU/h | 2637639.632 mW |
| 10000 BTU/h | 2930710.702 mW |
| 12000 BTU/h | 3516852.842 mW |
| 18000 BTU/h | 5275279.263 mW |
| 24000 BTU/h | 7033705.684 mW |
| 36000 BTU/h | 10550558.53 mW |
| 48000 BTU/h | 14067411.37 mW |
| 60000 BTU/h | 17584264.21 mW |
| 80000 BTU/h | 23445685.61 mW |
| 100000 BTU/h | 29307107.02 mW |
Where it's used
BTU per Hour are used for air-conditioner and heat-pump capacity (e.g. 12 000 BTU/h), while milliwatts appear in laser pointer and diode output. Both measure power (energy per unit time), so the conversion is a fixed factor.
BTU per Hour to other power units
| Conversion | 1 BTU/h equals |
|---|---|
| BTU per hour to watt | 0.2930710702 W |
| BTU per hour to milliwatt | 293.0710702 mW |
| BTU per hour to kilowatt | 0.0002930710702 kW |
| BTU per hour to megawatt | 2.930710702 × 10⁻⁷ MW |
| BTU per hour to horsepower | 0.0003930147789 hp |
| BTU per hour to metric horsepower | 0.0003984657624 PS |
| BTU per hour to refrigeration ton | 0.00008333333333 TR |
| BTU per hour to kilocalorie per hour | 0.2519957611 kcal/h |
| BTU per hour to foot-pound per second | 0.2161581284 ft·lbf/s |
Frequently asked questions
How many milliwatts are in 1 BTU per hour?
1 BTU/h = 293.0710702 mW.
How do I convert BTU per hour to milliwatts?
Multiply the value in BTU/h by 293.0710702. For example, 15 BTU/h × 293.0710702 = 4396.066053 mW.
Is the BTU/h to mW conversion exact?
Yes. Both units are defined exactly, so the ratio is exact; its decimal form does not terminate and is shown here to 10 significant figures (more with the precision selector).
Sources
- Guide for the Use of the International System of Units (SI), NIST Special Publication 811, 2008 Edition, National Institute of Standards and Technology , Appendix B.8, "British thermal unit_IT per hour".
- The International System of Units (SI), 9th edition (SI Brochure), Bureau International des Poids et Mesures , Table 7, SI prefixes.
Last reviewed: . Factors are stored exactly and computed with 50-digit decimal arithmetic. See how we verify conversion factors.
Cite this page
APA
Scientific Converters. (2026, October 15). Convert BTU per Hour to Milliwatts. Retrieved October 17, 2026, from https://scientificconverters.com/power/btu-per-hour-to-milliwatts/
IEEE
Scientific Converters, "Convert BTU per Hour to Milliwatts," scientificconverters.com. Accessed: Oct. 17, 2026. [Online]. Available: https://scientificconverters.com/power/btu-per-hour-to-milliwatts/