dBm to mW Converter
About This Calculator
Convert electric power units from decibel-milliwatts (dBm) or decibel-watts (dBW) to milliwatts (mW) or watts (W). Essential for RF engineering, telecommunications, and wireless communications.
Common dBm Values in Real Applications
Understanding dBm values helps interpret signal strength readings:
- Wi-Fi Signal Strength: -30 dBm (1 µW) is excellent, -70 dBm (0.0001 mW) is weak but usable, -90 dBm is typically unusable.
- Cell Phone Signal: -50 dBm is excellent, -80 dBm is good, -100 dBm is poor. Most phones display bars based on dBm.
- Bluetooth: Class 1 devices transmit at 20 dBm (100 mW), Class 2 at 4 dBm (2.5 mW), Class 3 at 0 dBm (1 mW).
- Wi-Fi Routers: Typically transmit at 20-23 dBm (100-200 mW) in the 2.4 GHz band.
- Fiber Optics: Optical power measured in dBm, with 0 dBm = 1 mW being a common reference.
dBm to mW Formula
The power P(mW) in milliwatts is equal to 10 raised to the power of the power P(dBm) in dBm, divided by 10:
P(mW) = 10(P(dBm)/10)
Therefore, 0 dBm = 100 = 1 mW
Example:
Convert 20 dBm to milliwatts:
P(mW) = 10(20/10) = 102 = 100 mW
dBW to W Formula
The power P(W) in watts is equal to 10 raised to the power of the power P(dBW) in dBW, divided by 10:
P(W) = 10(P(dBW)/10)
Example:
Convert 10 dBW to watts:
P(W) = 10(10/10) = 101 = 10 W
Relationship Between dBm and dBW
Since 1 W = 1000 mW:
- dBW = dBm − 30
- dBm = dBW + 30
Quick Reference Table
Common dBm to mW conversions. See complete table →
dBm to Milliwatts Conversion Table
-30 dBm to 40 dBm
Frequently Asked Questions
How do I convert dBm to mW?
To convert dBm to milliwatts, use the formula: mW = 10(dBm/10). For example, 20 dBm = 10(20/10) = 102 = 100 mW.
What is 0 dBm in milliwatts?
0 dBm equals exactly 1 milliwatt (1 mW). This is the reference point for the dBm scale. The formula gives: mW = 10(0/10) = 100 = 1 mW.
How do I convert dBW to watts?
To convert dBW to watts, use the formula: W = 10(dBW/10). For example, 10 dBW = 10(10/10) = 101 = 10 W.
What is the relationship between dBm and dBW?
dBW = dBm − 30 and dBm = dBW + 30. Since 1 W = 1000 mW, there is a 30 dB difference between the two scales. For example, 0 dBm = -30 dBW = 1 mW.
What is 20 dBm in milliwatts?
20 dBm = 100 mW. Using the formula: mW = 10^(20/10) = 10² = 100 mW. This is the typical transmit power of a Wi-Fi router.
What does -70 dBm mean for Wi-Fi?
-70 dBm equals 0.0001 mW (0.1 µW). This is considered a weak but usable Wi-Fi signal. Web browsing works, but streaming video may buffer. Signal below -80 dBm is usually unreliable.
How do I convert negative dBm to mW?
The same formula applies: mW = 10^(dBm/10). For example, -10 dBm = 10^(-10/10) = 10^(-1) = 0.1 mW. Negative dBm values represent power less than 1 mW.
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