My wireless sensor must stay under 100 mW to meet regulations. What is that in watts?

100 mW = 0.1 W. Many ISM-band transmitters are limited to 100 mW (20 dBm) EIRP for unlicensed operation.

I'm designing an IoT device that must last 1 year on a 3000 mAh battery at 3.3 V. How many milliwatts can I budget?

Energy = 3000 mAh × 3.3 V = 9900 mWh = 9.9 Wh. Over 8,760 hours (1 year), average power = 9900 ÷ 8760 ≈ 1.13 mW. Very tight — you'd need aggressive duty cycling.

A solar garden light has a 50 mW solar panel. How many watts is that, and is it enough?

50 mW = 0.05 W. A small LED indicator only needs 10–30 mW, so it can work for several hours on a charged battery, but won't power anything larger.

My LED driver spec says maximum 3 W. How do I check if my LEDs (each 350 mW) are within spec?

3 W = 3000 mW. At 350 mW per LED, you can safely drive 3000 ÷ 350 ≈ 8 LEDs at full brightness, or 6 LEDs with 20% headroom.

Watts to Milliwatts Converter

Enter a value to instantly convert between power units.

From

Precision4 dp

1 Watt = 1000 Milliwatt

Key Formulas

Kilowatt → Horsepower (mech)

hp = kW × 1.34102

Horsepower (mech) → Kilowatt

kW = hp × 0.7457

Watt → Kilowatt

kW = W × 0.001

Kilowatt → Watt

W = kW × 1000

Formula

mW = W × 1000

Electronic engineers work in milliwatts when designing battery-powered devices — a Bluetooth chip might consume 15 mW during transmission, and a microcontroller could sleep at 0.5 mW. Converting from watts makes sense when a datasheet lists maximum power in watts (e.g., 0.25 W resistor rating) but you need to budget per-component consumption in milliwatts. RF engineers also commonly express transmit power in mW or dBm.

Source: NIST SP 811, Table B.8

Last reviewed: 2026-06-11 · see our methodology

Frequently Asked Questions

Real-World Examples

A Bluetooth Low Energy module in active transmission mode draws about 0.05 W = 50 mW, allowing months of operation on a coin cell battery.

0.05 W = 50 mW

A standard through-hole resistor is rated 0.25 W = 250 mW maximum power dissipation — exceed this and it overheats.

0.25 W = 250 mW

A high-brightness white LED running at 1 W = 1000 mW produces roughly 80–100 lumens — equivalent to a small flashlight.

1 W = 1000 mW

A USB charger output is rated at 5 W = 5000 mW, the standard power for charging phones and small devices via USB-A.

5 W = 5000 mW

kw to hp hp to kw watts to kw kw to watts mw to kw kw to mw

Watts to Milliwatts Converter

Key Formulas

Formula

Frequently Asked Questions

Real-World Examples

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