BTU/hour to Milliwatts Converter
Enter a value to instantly convert between power units.
1 BTU/hour = 293.0711 Milliwatt
Key Formulas
Kilowatt → Horsepower (mech)
hp = kW × 1.34102Horsepower (mech) → Kilowatt
kW = hp × 0.7457Watt → Kilowatt
kW = W × 0.001Kilowatt → Watt
W = kW × 1000Formula
mW = BTU/h × 293.071Small thermal loads — body heat from occupants, heat dissipation from electronics, or heat output from small appliances — are sometimes quoted in BTU/h but need to be compared to milliwatt-scale electronic budgets. A person at rest generates about 400 BTU/h = 117,228 mW = 117 W of body heat. This conversion also appears in building physics when accounting for internal gains from small appliances and lighting.
Source: NIST SP 811, Table B.8
Last reviewed: · see our methodology
Frequently Asked Questions
Real-World Examples
1 BTU/h = 293 mW — useful for understanding the scale of very small thermal loads like a warm pipe or a single occupant at rest.
1 BTU/h = 293.1 mW
A small electric candle warmer rated 10 BTU/h = 2,931 mW = 2.93 W — consistent with a plug-in wax melter.
10 BTU/h = 2930.7 mW
A small LED under-cabinet light producing 50 BTU/h of heat = 14,654 mW = 14.7 W — significant for tight enclosed cabinet heat calculations.
50 BTU/h = 14653.6 mW
A 100 BTU/h heat gain through a window = 29,307 mW = 29.3 W — used in room-by-room HVAC load calculations.
100 BTU/h = 29307 mW