Aisha K.
Mar 12, 2026
Clean layout and the results update instantly. Exactly what I needed for a quick planning check.
Unit Converters
Decibel-milliwatts (dBm) to Watts Converter
watts = 10^((dBm − 30)/10). milliwatts = 10^(dBm/10).
P(W) = 10^((dBm − 30)/10). 0 dBm is 1 mW. 30 dBm is 1 W. Wi-Fi EIRP limits are a regulator’s problem; this is just the log.
dBm
dBm → W
0.001 W
0 dBm is 1 mW. Wi-Fi radios live well below a watt.
- dBm
- 0
- Milliwatts
- 1
Plain-English guide
Terms & how it works
Confused by a field? Read the short definitions here while you use the tool.
dBm
The “dBm” value used in this tool’s formula. Adjust it to see results update live.
How this calculator works
P(W) = 10^((dBm − 30)/10). 0 dBm is 1 mW. 30 dBm is 1 W. Wi-Fi EIRP limits are a regulator’s problem; this is just the log. watts = 10^((dBm − 30)/10). milliwatts = 10^(dBm/10). Example: 0 dBm → 0.001 W (1 mW). 30 dBm → 1 W. −30 dBm → 1 µW.
watts = 10^((dBm − 30)/10). milliwatts = 10^(dBm/10).
Example: 0 dBm → 0.001 W (1 mW). 30 dBm → 1 W. −30 dBm → 1 µW.
When to use this dBm to Watts
Common use cases
- P(W) = 10^((dBm − 30)/10). 0 dBm is 1 mW. 30 dBm is 1 W. Wi-Fi EIRP limits are a regulator’s problem; this is just the log.
- Sanity-check with this case: 0 dBm → 0.001 W (1 mW). 30 dBm → 1 W. −30 dBm → 1 µW.
- The relationship is: watts = 10^((dBm − 30)/10). milliwatts = 10^(dBm/10).
Localized examples
- Unit Converters: the example on this page uses the same formula as the widget.
What you get
- Fields: dBm
- watts = 10^((dBm − 30)/10). milliwatts = 10^(dBm/10).
- Example on the page: 0 dBm → 0.001 W (1 mW). 30 dBm → 1 W. −30 dBm → 1 µW.
How to Convert dBm to Watts Step-by-Step
- 1Enter dBm. Use the values you have, not a catalog average, unless that is all you know.
- 2watts = 10^((dBm − 30)/10). milliwatts = 10^(dBm/10).
- 3Worked case: 0 dBm → 0.001 W (1 mW). 30 dBm → 1 W. −30 dBm → 1 µW.
- 4Check which dictionary the other person is using — US or UK, decimal or 1,024 — then trust the number.
Governing formula
watts = 10^((dBm − 30)/10). milliwatts = 10^(dBm/10).
0 dBm → 0.001 W (1 mW). 30 dBm → 1 W. −30 dBm → 1 µW.
Example: set dBm = 0, then read the result.
Variable definitions
- value
dBm
The “dBm” field. Default 0; typical range -120–60.
- The conversion (watts = 10^((dBm − 30)/10). milliwatts = 10^(dBm/10).) does not pick US vs UK gallons, SI vs binary megabytes, or Mach at altitude for you. Read the footnote on the page.
- Nothing here is uploaded for the calculation itself.
Frequently Asked Questions
dBW is referenced to 1 W. dBm is referenced to 1 mW. Subtract 30 to go dBm → dBW.
Related calculators
Unit Converters
- Appliance Running CostCost = watts × hours / 1000 × $/kWh. A 1,500 W space heater for 4 hours at $0.16/kWh is $0.96. The supply rate on the bill is the one that matters, not a national average.
- Decibels to W/m²I = 10⁻¹² × 10^(L/10) W/m². 0 dB SPL is the quiet threshold, 60 dB a chat, 120 dB a pain rumor. Loudness is not intensity; +10 dB is 10× intensity and roughly twice as loud to a human ear.
- Horsepower to WattsMechanical horsepower is 745.7 W. A 150 hp engine is 112 kW. Metric PS is 735.5 W — close, not the same. Peak dyno hp is not what the wheels see. Convert the number on the spec sheet, then stay humble.
- Kilowatts to HorsepowerDivide kW by 0.7457 (or multiply by 1.341). A 100 kW electric motor is 134 hp. EV brochures already did this; ICE dyno sheets sometimes did not. Metric PS is 1.36 hp per kW — close enough to start a fight.
- SI Watt Prefix ConverterPhone chargers in watts, homes in kilowatts, plants in megawatts, grids in gigawatts. A 1.5 kW kettle is 1,500 W. Terawatts show up in climate-scale diagrams, not in a breaker panel.
- Solar Panel Daily kWhkWh/day ≈ (array W / 1000) × peak sun hours. A 400 W panel in 4.5 PSH is 1.8 kWh before dirt, heat, and inverter loss (often 0.75–0.85). NREL sun-hour maps beat a guess.
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Reviews & Ratings
See what others think about this tool, then leave your own rating to help improve CalculioHub.
4.8
out of 5.0
4 reviews
Daniel R.
Feb 28, 2026
Very usable on mobile. Would love a save/export option later, but the math feels solid.
Priya S.
Feb 3, 2026
The FAQ section answered my questions before I even had to search. Smooth dark mode too.
Marcus L.
Jan 19, 2026
Simple inputs, clear outputs. This replaced three bookmarks I used to juggle.
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