About

In radio frequency (RF) engineering and telecommunications, handling power levels that span huge orders of magnitude is routine. A satellite receiver might deal with picowatts while the uplink transmitter blasts kilowatts. Using linear units like Watts becomes cumbersome and prone to calculation errors in these scenarios. The dBW (decibel-watt) scale compresses these values into a logarithmic format, making link budget addition and subtraction possible.

This tool converts absolute power in Watts directly to dBW. Unlike dBm, which references milliwatts, dBW references 1 Watt. This distinction is critical in high-power applications such as radar systems, broadcast transmitters, and deep-space communication uplinks. Engineers utilize this conversion to determine if a signal meets the threshold for receiver sensitivity or exceeds regulatory Effective Isotropic Radiated Power (EIRP) limits.

Formulas

The conversion utilizes the base-10 logarithm. Since dBW is referenced to 1 Watt, the formula is direct:

P_(dBW) = 10 × log₁₀P_(W)

To convert backwards from dBW to Watts, the inverse exponential function is used:

P_(W) = 10^P_(dBW)10

Note on constraints: The logarithm of a non-positive number is undefined. Therefore, P_(W) must be > 0.

Reference Data

Power (Watts)	Power (dBW)	Signal Classification
0.001 W	-30 dBW	Low Power (ISM Band)
0.01 W	-20 dBW	Short Range Device
0.1 W	-10 dBW	Wi-Fi Transmitter
0.5 W	-3.01 dBW	Mobile Handset
1 W	0 dBW	Reference Point
2 W	3.01 dBW	Portable Radio
10 W	10 dBW	Mobile Base Station
50 W	16.99 dBW	High Power Amplifier
100 W	20 dBW	FM Broadcast Exciter
1000 W	30 dBW	Radar Pulse
1000000 W	60 dBW	Megawatt Class

Frequently Asked Questions

Yes. Any power level below 1 Watt results in a negative dBW value. For example, 100 milliwatts (0.1 W) is -10 dBW. Negative values indicate the signal is weaker than the reference of 1 Watt, not that the energy is negative.

The difference is the reference unit. dBW references 1 Watt, while dBm references 1 milliwatt. Since 1 Watt = 1000 milliwatts, the relationship is constant: P(dBm) = P(dBW) + 30. For instance, 0 dBW equals 30 dBm.

Logarithms are undefined for zero. In physical terms, 0 Watts represents the complete absence of signal. On a logarithmic scale, as power approaches zero, the dB value approaches negative infinity (-∞).

No. Antenna gain is measured in dBi (isotropic) or dBd (dipole), which are relative ratios, not absolute power levels. dBW is strictly for absolute power.