Milliwatts to BTU/hr Converter
Enter the power in milliwatts below to convert it to btu/hr.
Convert Milliwatts to BTU/hr
Enter a value in milliwatts (mW) to convert to btu/hr (BTU/hr).
Milliwatt to BTU per Hour Conversion Table
Table showing various milliwatt measurements converted to btu/hr. Click any preset value or arrow to load it into the converter.
| Milliwatts (mW) | BTU/hr (BTU/hr) |
|---|---|
| 1 mW | 0.0034121 BTU/hr |
| 2 mW | 0.0068243 BTU/hr |
| 2.5 mW | 0.0085304 BTU/hr |
| 5 mW | 0.0170607 BTU/hr |
| 10 mW | 0.0341214 BTU/hr |
| 15 mW | 0.0511821 BTU/hr |
| 20 mW | 0.0682428 BTU/hr |
| 25 mW | 0.0853035 BTU/hr |
| 30 mW | 0.1023642 BTU/hr |
| 50 mW | 0.1706071 BTU/hr |
How to Convert Milliwatts to BTU/hr
To convert milliwatts to btu/hr, multiply the power by the following conversion ratio: 0.0034121 btu/hr/milliwatt.
Since one milliwatt is equal to 0.0034121 btu/hr, you can use this simple formula to convert:
The power in btu/hr is equal to the power in milliwatts multiplied by 0.0034121.
For example, here's how to convert 5 milliwatts to btu/hr using the formula above.
How Many BTU/hr Are in a Milliwatt?
There are 0.0034121 btu/hr in a milliwatt, which is why we use this value in the formula above.
Our milliwatt to btu per hour calculator automatically converts your power measurements with full decimal and scientific precision across US customary, imperial, and SI metric standards.
Milliwatts and btu/hr are both units used to measure power. Keep reading to learn more about each unit.
What Is a Milliwatt?
A milliwatt is a unit of power equal to 1/1,000 of a watt (0.001 W). One-thousandth of a Watt. [1]
The milliwatt is classified as a metric and SI-compatible unit of power. Milliwatts can be abbreviated as mW; for example, 1 milliwatt can be written as 1 mW.
In the metric system, "milli" is the standard SI prefix for thousandths, or 10⁻³. This makes the milliwatt (mW) a convenient decimal multiple of the watt (W).
In practice, milliwatts (mW) are widely used across fine-tolerance laboratory, analytical, and micro-scale power measurements within SI metric workflows, engineering documentation, and technical data sheets.
What Is a BTU per Hour?
A btu per hour is a unit of power equal to 0.2930711 watts (W), the base unit for power. HVAC thermal rate (1 W ≈ 3.41214 BTU/hr). [2]
The btu per hour is classified as a US customary and imperial unit of power. BTU/hr can be abbreviated as BTU/hr; for example, 1 btu per hour can be written as 1 BTU/hr.
When working with btu/hr (BTU/hr) in formulas or technical specifications, always verify whether your target system uses SI metric, US customary, or British imperial standards.
In practice, btu/hr (BTU/hr) are widely used across standard power applications within US customary and imperial workflows, engineering documentation, and technical data sheets.
When converting power between milliwatts (mW) and btu/hr (BTU/hr), keep full floating-point precision (1 mW = 0.0034121 BTU/hr; 1 BTU/hr = 293.07107 mW) during intermediate calculations and round only the final btu per hour figure to match your instrument tolerance.
More Milliwatt & BTU per Hour Conversions
Need to calculate in the opposite direction? Use our btu/hr to milliwatts calculator to switch your starting unit immediately. You can also explore related tools such as converting btu/hr to milliwatts, converting tons of refrigeration to btu/hr, or converting watts to horsepower (hp).
Frequently Asked Questions
References
- [1]NIST SP 811 StandardNIST SP 811 (NIST SP 811 App. B.9 (Power & Radiant Flux))·Power Metrology Standard — Milliwatts (mW) to BTU/hr (BTU/hr)
- [2]NIST CUU SpecificationNIST CUU (Derived SI Unit: Watt (W))·Unit Specifications: Milliwatt (mW) & BTU per Hour (BTU/hr)
- [3]BIPM ReferenceBIPM (SI Brochure (9th Ed.) — Power)·Conversion Factors & Mathematical Basis (mW to BTU/hr)