dBm to mW Converter

How to convert dBm to mW?

dBm is a logarithmic power *ratio* referenced to 1 mW; mW is a *linear* power. They are different kinds of numbers, and the conversion is exponential, not linear: P(mW) = 10^(P(dBm)/10). Because the inverse of the log scale is exponential, equal additive steps on the dBm side become geometric multiplications on the mW side — every +3 dB doubles mW, every +10 dB multiplies by ten, and 0 dBm is exactly 1 mW. Critically, dBm values can be negative: receive-side sensitivity in wireless systems is routinely −70 dBm to −100 dBm (= 100 pW down to 0.1 pW), and these negative numbers are perfectly physical. Our tool computes mW = 10^(dBm/10) using JavaScript's Math.pow, which is correctly rounded to the nearest IEEE-754 double for all finite inputs; the result domain is the entire positive real line (0+ to +∞). Common anchor values to keep handy: −30 dBm = 0.001 mW = 1 µW; −20 dBm = 0.01 mW; −10 dBm = 0.1 mW; 0 dBm = 1 mW; 10 dBm = 10 mW; 20 dBm = 100 mW; 23 dBm ≈ 200 mW (cellular handset peak); 30 dBm = 1 W; 40 dBm = 10 W; 50 dBm = 100 W; 60 dBm = 1 kW (broadcast tower). This converter is used daily for link-budget arithmetic ("if the transmitter is +20 dBm, the antenna gain +6 dBi, the path loss −80 dB, what arrives at the receiver?") and for translating datasheet sensitivities into the wattage values an analog designer needs.

P_(mW) = P_(dBm) × 1

Worked example

An LTE handset receives a tower signal at −95 dBm. To find the linear power: P(mW) = 10^(−95/10) = 10^(−9.5) ≈ 3.162 × 10⁻¹⁰ mW = 3.162 × 10⁻¹³ W = 316.2 femtowatts. Despite being femtowatts, this is well above the noise floor of a typical −174 dBm/Hz thermal noise source integrated over a 10 MHz bandwidth (kTB ≈ −104 dBm), giving roughly 9 dB of SNR — enough for QPSK modulation.

P_(mW) = 1 dBm × 1 = 1 mW

How many mW in a dBm?

0 dBm equals exactly 1 mW. Because the relationship is exponential, equivalents for other values follow 10^(dBm/10): −10 dBm = 0.1 mW; +10 dBm = 10 mW; +20 dBm = 100 mW; +30 dBm = 1000 mW = 1 W.

Can dBm be negative?

Yes — negative dBm just means the power is less than 1 mW. Wi-Fi receivers see −50 dBm (strong) to −80 dBm (weak) all day. The minus sign carries through the exponent: 10^(−85/10) = 10^(−8.5) ≈ 3.16 × 10⁻⁹ mW.

What is dBm and where is it used?

dBm (decibel-milliwatt) is a logarithmic unit of power used in radio frequency and microwave engineering, telecommunications, and wireless communications.

Why convert dBm to mW?

Converting dBm to mW is needed for RF engineering, antenna design, wireless communications, and working with equipment that uses milliwatts as the standard power unit.

Popular dBm to mW conversion table