dBm / Power Converter
Convert between dBm, dBW, Watt, milliwatt, microwatt and power ratios (dB).
Quick examples
dBm Conversion Formulas
dBm is a logarithmic power unit referenced to 1 milliwatt. It is the standard unit for RF power levels in wireless systems.
P(dBm) = 10 × log₁₀(P(mW))
P(mW) = 10 ^ (P(dBm) / 10)
P(dBW) = P(dBm) − 30
Power ratio = 10 ^ (dB / 10)
Voltage ratio = 10 ^ (dB / 20)
Transmit power in dBm is a key input to an RF link budget — use the link budget calculator to determine coverage range from your transmit power and antenna configuration.
| dBm | mW | Watt | Typical use |
|---|---|---|---|
| −120 dBm | 1 × 10⁻⁹ mW | 1 pW | LTE RX sensitivity floor |
| −30 dBm | 0.001 mW | 1 µW | Weak received signal |
| 0 dBm | 1 mW | 0.001 W | Reference level |
| 30 dBm | 1000 mW | 1 W | Small cell TX power |
| 46 dBm | 39 810 mW | ~40 W | LTE macro base station |
Worked Example
Convert a base station transmit power of 43 dBm to watts and dBW.
P(mW) = 10^(43/10) = 10^4.3 ≈ 19 953 mW ≈ 20 W
P(dBW) = 43 − 30 = +13 dBW
Interpretation: 43 dBm is approximately 20 W. This is the per-port transmit power of a typical LTE macro base station. With an 18 dBi antenna and 2 dB cable loss, EIRP = 43 + 18 − 2 = 59 dBm (794 W EIRP).
Use EIRP with the link budget calculator to determine the maximum allowable path loss and cell coverage range.
Frequently Asked Questions
What is dBm?▾
dBm is a unit of power expressed in decibels relative to 1 milliwatt. It is used throughout RF and wireless engineering because it converts multiplicative gain/loss chains into simple addition and subtraction. A positive dBm value means more than 1 mW; a negative value means less than 1 mW.
What is the difference between dBm and dBW?▾
Both are logarithmic power units — dBm references 1 milliwatt and dBW references 1 Watt. To convert: dBW = dBm − 30. For example, 46 dBm = 16 dBW. dBm is more common in RF work at component and system level; dBW is used in satellite link budgets and ITU-R calculations.
Why is the voltage ratio formula different (÷20 instead of ÷10)?▾
Power is proportional to voltage squared (P ∝ V²). Taking the log of V² = 2 log V, which is why the voltage ratio uses 20·log₁₀ while the power ratio uses 10·log₁₀. This means 6 dB is approximately a 2× voltage ratio, but a 4× power ratio.
What is a typical LTE handset transmit power?▾
LTE UE (handset) maximum transmit power is 23 dBm (200 mW) for power class 3, which is the most common. Some IoT devices use power class 5 (20 dBm / 100 mW). LTE macro base stations typically transmit at 43–46 dBm (20–40 W) per antenna port.