📡 dBm to Watts Calculator
Translate RF power between logarithmic (dBm) and linear (watts/milliwatts) scales.
Ideal for wireless engineers, IoT developers, and students crossing between link budgets and real power measurements.
dBm is a decibel scale referenced to 1 milliwatt.
30 dBm equals
1 watts
(1,000 milliwatts)
Reference Table
Weak signal
-30 dBm = 0.000001 W (0.001 mW)
1 milliwatt reference
0 dBm = 0.001 W (1 mW)
10 milliwatts
10 dBm = 0.01 W (10 mW)
1 watt
30 dBm = 1 W (1,000 mW)
How to Use This Calculator
Choose a direction
Toggle between converting a dBm reading to watts or a linear power level to dBm.
Enter the value
Provide the measured or specified power. dBm accepts any real number; watt input must be positive for a meaningful dBm result.
Use the equivalents
Copy watts, milliwatts, or dBm directly into link budgets, datasheets, or calibration notes.
Formula
Watts = 10^(dBm ÷ 10) ÷ 1000
dBm = 10 × log₁₀(watts × 1000)
Milliwatts = Watts × 1000
dBm is referenced to 1 milliwatt; the formulas convert between logarithmic and linear power scales.
Use the formula breakdown to confirm the calculation logic or perform the conversion manually if needed.
Full Description
RF and microwave engineers often see power expressed in dBm because it spans wide dynamic ranges compactly. When sizing amplifiers, antennas, or attenuators, you still need linear watts or milliwatts. This calculator bridges those views with high precision.
The tool handles very small and very large powers gracefully. Negative dBm values correspond to microwatt or nanowatt signals, while high positive values reach transmit power levels. All calculations use base-10 logarithms consistent with communications textbooks.
Keep it open while tuning lab instruments or reviewing wireless certification reports to avoid manual log conversions and rounding mistakes.
Frequently Asked Questions
Why does the calculator require positive watts for dBm?
Logarithms of zero or negative values are undefined. Real-world power is non-negative, so enter a value greater than zero.
Can it convert dBW or dBi?
This page focuses on dBm (reference 1 mW). You can adapt the formulas: dBW uses 1 watt as the reference. dBi relates to antenna gain, not power.
What about voltage conversions?
Voltage depends on impedance. For 50 Ω systems, use V = √(P × R). Add a voltage section if you frequently need that conversion.
How accurate are the logarithmic conversions?
Calculations use JavaScript’s double-precision floats, providing more than enough accuracy for RF design and measurement work.