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RF and telecom equipment specify power in dBm — a logarithmic decibel scale relative to 1 milliwatt — rather than watts, because it makes very large power ratios (like signal gain and loss over a long cable run) much easier to add and subtract. This tool converts between dBm and watts/milliwatts in either direction.
How it works
P(mW) = 10^(dBm/10), and P(W) = P(mW) / 1000. The reverse direction uses dBm = 10 × log10(P in mW).
- Enter value.
- Enter conversion direction.
- Click Calculate to see your results.
Examples
A common reference point
30 dBm equals exactly 1000 mW (1 watt) — a standard reference value in RF engineering.
Who should use it
- Converting a Wi-Fi or cellular transmitter's dBm rating into a more intuitive watt figure.
- RF link-budget calculations.
Industry applications
- Telecommunications and RF engineering
- Wireless networking
- Broadcast engineering
Advantages
- Handles both directions (dBm to watts and watts to dBm).
- Shows the intermediate milliwatt value alongside the final watt figure.
Limitations
- Watts-to-dBm conversion requires a positive power value, since the logarithm of zero or a negative number is undefined.
Common mistakes to avoid
- Confusing dBm (an absolute power level relative to 1 mW) with plain dB (a relative ratio with no fixed reference point) — they are not interchangeable.
Best practices
- When adding up gains and losses across an RF signal chain, work entirely in dBm/dB, then convert to watts only at the very end for a final power reading.
Tips
- A handy mental shortcut: every +10 dBm multiplies power by 10x, and every +3 dBm roughly doubles it.