dBm to Watt Converter
Convert dBm to watts and back — the standard power unit for RF, wireless, and telecommunications engineering.
Reviewed October 7, 2026 Runs in your browser — inputs are never stored
Watts (W)
1.000000e-3 Watts (W)
= 1.000000e+0 mW
Reference table
| dBm | Watts | mW | Application |
|---|---|---|---|
| -130 | 1×10⁻¹³ | 1×10⁻¹⁰ | GPS signal |
| -100 | 1×10⁻¹⁰ | 1×10⁻⁷ | Wi-Fi (weak) |
| -60 | 1×10⁻⁶ | 0.001 | Wi-Fi (good) |
| -20 | 0.01 | 10 | Bluetooth |
| 0 | 0.001 | 1 | Standard reference |
| 20 | 0.1 | 100 | Low power TX |
| 30 | 1 | 1,000 | 1 W transmitter |
| 40 | 10 | 10,000 | 10 W transmitter |
This tool provides general unit conversions for everyday and educational use. For regulated, legal, or scientific applications, verify conversion factors against the applicable official standard.
About the dBm to Watt Converter
The dBm to watt converter changes power between decibel-milliwatts and watts. dBm expresses power relative to 1 milliwatt on a logarithmic scale: 0 dBm = 1 mW, every +10 dBm multiplies power by ten, and +3 dBm roughly doubles it. It is the standard unit for radio transmitters, Wi-Fi signal strength and fibre optics.
How to use it
- 1Choose dBm → watts or watts → dBm.
- 2Enter the value.
- 3Read the power in watts, milliwatts or dBm.
- 4Copy, share or print the result with the buttons below it.
Worked example
20 dBm = 100 mW = 0.1 W, while a weak Wi-Fi signal of −70 dBm is just 0.1 nanowatt (10⁻¹⁰ W).
How it works
Formula
P(W) = 10^((P(dBm) − 30) / 10)
P(dBm) = 10 × log₁₀(P(W)) + 30
What is dBm?
dBm is decibels relative to 1 milliwatt: 0 dBm = 1 mW. Used in RF, Wi-Fi, cellular, and optical communications.
Common use cases
- Interpreting Wi-Fi and mobile signal strength
- Radio and antenna calculations
- Fibre-optic link budgets
Frequently asked questions
A:0 dBm = 1 mW = 0.001 W (reference level).
A:Strong: −50 to −67 dBm · OK: −68 to −70 dBm · Weak: below −70 dBm · Unusable: below −90 dBm.
Reviewed for accuracy · Last updated October 7, 2026
Conversion factors are based on internationally defined SI units and standard metric/imperial equivalence tables.
CalcWisee Editorial Team
Calculator development and formula review
CalcWisee is an independent site founded by Ayman. Every calculator is built from a published formula or official definition, tested against hand-worked examples before it goes live, and corrected promptly when a reader reports an issue to ayman@calcwisee.com.
Expertise: Financial mathematics, Health and fitness formulas, Applied mathematics, Unit conversion standards
References & sources
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