Horsepower to Milliwatts Converter
Enter the power in horsepower below to convert it to milliwatts.
Convert Horsepower (hp) to Milliwatts
Enter a value in horsepower (hp) (hp) to convert to milliwatts (mW).
Horsepower to Milliwatt Conversion Table
Table showing various horsepower measurements converted to milliwatts. Click any preset value or arrow to load it into the converter.
| Horsepower (hp) (hp) | Milliwatts (mW) |
|---|---|
| 0.0000001 hp | 0.07457 mW |
| 0.0000002 hp | 0.14914 mW |
| 0.0000003 hp | 0.22371 mW |
| 0.0000004 hp | 0.2982799 mW |
| 0.0000005 hp | 0.3728499 mW |
| 0.0000006 hp | 0.4474199 mW |
| 0.0000007 hp | 0.5219899 mW |
| 0.0000008 hp | 0.5965599 mW |
| 0.0000009 hp | 0.6711299 mW |
| 0.00000001 hp | 0.007457 mW |
How to Convert Horsepower to Milliwatts
To convert horsepower to milliwatts, multiply the power by the following conversion ratio: 745,699.8715823 milliwatts/horsepower.
Since one horsepower is equal to 745,699.8715823 milliwatts, you can use this simple formula to convert:
The power in milliwatts is equal to the power in horsepower multiplied by 745,699.8715823.
For example, here's how to convert 5 horsepower to milliwatts using the formula above.
How Many Milliwatts Are in a Horsepower?
There are 745,699.8715823 milliwatts in a horsepower, which is why we use this value in the formula above.
Our horsepower to milliwatt calculator automatically converts your power measurements with full decimal and scientific precision across US customary, imperial, and SI metric standards.
Horsepower and milliwatts are both units used to measure power. Keep reading to learn more about each unit.
What Is a Horsepower?
A horsepower is a unit of power equal to 745.6998716 watts (W), the base unit for power. Imperial mechanical horsepower (550 ft·lbf/s ≈ 745.7 W). [1]
The horsepower is classified as a US customary and imperial unit of power. Horsepower can be abbreviated as hp; for example, 1 horsepower can be written as 1 hp.
When working with horsepower (hp) in formulas or technical specifications, always verify whether your target system uses SI metric, US customary, or British imperial standards.
In practice, horsepower (hp) are widely used across standard power applications within US customary and imperial workflows, engineering documentation, and technical data sheets.
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. [2]
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.
When converting power between horsepower (hp) and milliwatts (mW), keep full floating-point precision (1 hp = 745,699.8715823 mW; 1 mW = 0.000001341 hp) during intermediate calculations and round only the final milliwatt figure to match your instrument tolerance.
More Horsepower & Milliwatt Conversions
Need to calculate in the opposite direction? Use our milliwatts to horsepower (hp) calculator to switch your starting unit immediately. You can also explore related tools such as converting milliwatts to horsepower (hp), converting horsepower (hp) to watts, or converting horsepower (hp) to kilowatts.
Convert from Horsepower
Frequently Asked Questions
References
- [1]NIST SP 811 StandardNIST SP 811 (NIST SP 811 App. B.9 (Power & Radiant Flux))·Power Metrology Standard — Horsepower (hp) (hp) to Milliwatts (mW)
- [2]NIST CUU SpecificationNIST CUU (Derived SI Unit: Watt (W))·Unit Specifications: Horsepower (Mechanical) (hp) & Milliwatt (mW)
- [3]BIPM ReferenceBIPM (SI Brochure (9th Ed.) — Power)·Conversion Factors & Mathematical Basis (hp to mW)