dBm to Watts Converter

Below you will find the dBm to watts formula, a full 0 to 60 dBm chart, the watts to dBm formula, Excel formulas and the power levels you meet in Wi-Fi, Bluetooth and cellular base stations.

dBm to Watts Calculator: How to Use It

1. Pick a direction. Use the dBm to Watts tab, or switch to Watts to dBm.
2. Enter your value. For dBm to watts, you can also choose dBW as the input unit. For watts to dBm, choose W, mW or kW.
3. Click Convert. The result shows the power in watts or dBm, plus the same value in W, mW, dBm and dBW.

Click any row in the quick values table to load that value into the calculator.

What Is dBm?

dBm stands for decibels relative to one milliwatt. It measures power on a logarithmic scale with a fixed reference of 1 mW, so 0 dBm = 1 mW. The “dB” part expresses a ratio, and the “m” ties that ratio to 1 milliwatt. That makes dBm an absolute power unit. A plain dB value only tells you how much bigger or smaller one quantity is than another.

When an engineer says a transmitter puts out 30 dBm, they mean an exact power: 1 watt. You will see dBm on spectrum analyzers, power meters, Wi-Fi and Bluetooth datasheets, cellular link budgets, fiber optics and satellite links.

dBm to Watts Formula

Invert the dBm definition and you get the dBm to watts formula:

For milliwatts, drop the 30:

You divide by 10 because the decibel scale works in tenths of a power of ten. You subtract 30 (or divide by 1,000) because the reference is 1 milliwatt, and 1 watt is 1,000 milliwatts.

How to Convert dBm to Watts (Step by Step)

Take 23 dBm, the maximum uplink power of an LTE phone:

A quick mental check uses the 3 dB and 10 dB rules. Adding 3 dB doubles the power, and adding 10 dB multiplies it by ten. So 23 dBm is 20 dBm (100 mW) plus 3 dB, which gives 200 mW.

dBm to Watts Formula in Excel

Put your dBm value in cell A2 and use these formulas. They work the same way in Google Sheets.

Small watt values can show as zero. Format the cells with a number format such as 0.000000 or use scientific notation. In MATLAB or Python, the same formula reads P = 10.^((dBm-30)/10) and P = 10**((dBm-30)/10).

dBm to Watts Conversion Chart (0 to 60 dBm)

This dBm to watts table covers every whole number from 0 to 60 dBm, plus common negative and high values. The highlighted rows are the values people search for most. Scroll inside the table to see all rows.

Typical Power Levels by Application

dBm to mW (Milliwatts)

Converting dBm to mW is one step shorter than dBm to watts, because dBm already uses 1 mW as its reference:

So 10 dBm = 10 mW, 20 dBm = 100 mW and 30 dBm = 1,000 mW. Negative values give fractions of a milliwatt: −10 dBm = 0.1 mW and −30 dBm = 0.001 mW (1 µW). The calculator shows the mW value under every result.

To go back from mW to dBm, use dBm = 10 × log₁₀(P in mW). For example, 50 mW = 17 dBm and 0.5 mW = −3 dBm.

Watts to dBm Converter and Formula

To convert watts to dBm, multiply by 1,000 to get milliwatts, then take 10 times the base 10 logarithm:

Use the Watts to dBm tab in the calculator, or check the common values below:

Notice how the dBm scale squeezes a huge range into small numbers. One milliwatt to 100 watts covers a factor of 100,000, yet it spans only 0 to 50 dBm.

dBm to dBW and dBW to dBm

dBW uses 1 watt as its reference instead of 1 milliwatt. One watt is 1,000 mW, which is exactly 30 dB, so the conversion needs no logarithms:

For example, 46 dBm = 16 dBW = 40 W, 30 dBm = 0 dBW = 1 W, and 0 dBm = −30 dBW = 1 mW. Choose dBW as the input unit in the calculator to convert dBW straight to watts.

dB vs dBm vs Watt

These three units often get mixed up:

• Watt (W) is a linear unit of power. Double the number and you double the power.
• dBm is a logarithmic unit of absolute power with a 1 mW reference. Add 3 dB and you double the power.
• dB is a ratio with no fixed reference. It describes gain or loss, such as a 20 dB amplifier or 3 dB of cable loss.

Why Engineers Use dBm Instead of Watts

It compresses a huge range. Real signals run from about 10⁻¹⁵ W at a satellite receiver to kilowatts at a broadcast transmitter. In dBm that is roughly −120 dBm to +70 dBm, a range you can read at a glance.

Gains and losses add up. In watts, every amplifier, cable and splitter multiplies the power. In decibels you just add. A chain with +15 dB amplifier gain, −3 dB cable loss, +20 dB power amplifier gain and −6 dB splitter loss gives 15 − 3 + 20 − 6 = 26 dB. The linear version, 31.6 × 0.5 × 100 × 0.25 ≈ 398, is much harder to do in your head.

It is the industry standard. Spectrum analyzers, power meters, signal generators and datasheets all report in dBm.

One trap: you cannot add two dBm values like watts. Two 30 dBm (1 W) signals combine to 2 W, which is 33 dBm, not 60 dBm.

Base Station Power: 40, 43, 46 and 48 dBm in Watts

Telecom engineers meet these values every day on radio datasheets and site drawings. Here is what they mean in watts:

Two points matter on site. First, these numbers usually describe power at the radio port, before feeder loss and antenna gain. EIRP adds the antenna gain and subtracts cable losses. Second, a 3 dB step doubles the power, so moving from 43 dBm to 46 dBm takes a radio from 20 W to 40 W. To estimate how far that power reaches, use our free space path loss calculator.

Where You Will Meet dBm Values

Wi-Fi and wireless networking

Many Wi-Fi routers transmit around 20 dBm (100 mW), with limits set by each region. A phone reading of −65 dBm equals about 316 picowatts, and modern receivers decode it with ease. See the Wi-Fi Alliance for standards information.

Cellular, LTE and 5G

LTE phones transmit at up to 23 dBm (200 mW). Base stations use 43 to 46 dBm (20 to 40 W) per antenna port, and some 5G radios go higher.

Bluetooth and IoT

Bluetooth Class 1 devices transmit up to 20 dBm (100 mW), Class 2 at 4 dBm (2.5 mW) and Class 3 at 0 dBm (1 mW). Many IoT sensor nodes run between −10 and +10 dBm. The Bluetooth SIG specifications define the power classes. For battery powered nodes, our battery life calculator shows how transmit power affects runtime. If you design your own RF board, read our 2.4 GHz PCB antenna design guide.

Broadcast, radar and satellite

Low power FM stations run at about 50 dBm (100 W), and large stations reach 80 dBm (100 kW) of effective radiated power. Radar transmitters work at 70 dBm (10 kW) and above, while satellite downlinks can arrive near −100 dBm (0.1 pW). The FCC FM radio pages list licensed power levels in the United States.

dBm to Watts FAQ

How many watts is 46 dBm?

46 dBm is about 39.8 W, which most datasheets round to 40 W. It equals 16 dBW and is a common output per antenna port for macro base station radios.

What is 0 dBm in watts?

0 dBm equals 1 milliwatt, or 0.001 W. It is the reference point of the whole dBm scale.

What is 30 dBm in watts?

30 dBm equals exactly 1 W, because 10 raised to the power (30 minus 30) divided by 10 is 1. It is also 0 dBW.

What is 20 dBm in watts?

20 dBm equals 0.1 W, or 100 mW. Many Wi-Fi routers and Bluetooth Class 1 devices transmit at this level.

What is 43 dBm in watts?

43 dBm is about 19.95 W, usually written as 20 W. It is a typical macro base station output per antenna port.

What is the formula for dBm to watts?

Use P(W) = 10^((dBm minus 30) / 10). For milliwatts, use P(mW) = 10^(dBm / 10).

How do you convert dB to watts?

A plain dB value is a ratio, so it needs a reference before it becomes watts. If the value is in dBm, use P(W) = 10^((dBm minus 30) / 10). If it is in dBW, use P(W) = 10^(dBW / 10).

What is 0.5 W in dBm?

0.5 W is about 27 dBm (26.99 dBm). Use dBm = 10 × log10(P in watts × 1000).

How do I convert dBm to watts in Excel?

With the dBm value in cell A2, use =10^((A2-30)/10) for watts or =10^(A2/10) for milliwatts. For watts to dBm, use =10*LOG10(B2*1000).

What is the difference between dBm and dBW?

dBm uses 1 milliwatt as its reference and dBW uses 1 watt. They differ by exactly 30, so dBW = dBm minus 30 and dBm = dBW + 30.