Loading Calculator...
Please wait a moment
Please wait a moment
Convert decibel-milliwatts (dBm) to watts (W) instantly. Free online RF power unit converter with formula, conversion table, and practical examples for wireless communications and radio frequency applications.
W = 10((dBm - 30) / 10)
Or equivalently: W = 1 mW × 10(dBm / 10)
30 dBm = 1 W
| dBm | Watts | Common Application |
|---|---|---|
| -30 dBm | 0.000001 W (1 µW) | Weak Wi-Fi signal |
| -20 dBm | 0.00001 W (10 µW) | Minimum usable signal |
| -10 dBm | 0.0001 W (100 µW) | Good cell phone signal |
| 0 dBm | 0.001 W (1 mW) | Reference level |
| 10 dBm | 0.01 W (10 mW) | Bluetooth transmitter |
| 20 dBm | 0.1 W (100 mW) | Wi-Fi router output |
| 27 dBm | 0.5 W (500 mW) | High-power Wi-Fi |
| 30 dBm | 1 W | Cell phone base station |
| 40 dBm | 10 W | Two-way radio |
| 50 dBm | 100 W | FM radio transmitter |
| 60 dBm | 1,000 W (1 kW) | Broadcast transmitter |
| 70 dBm | 10,000 W (10 kW) | High-power broadcast |
dBm (decibel-milliwatts) is a logarithmic unit of measurement used to express power levels in radio frequency (RF) and telecommunications systems. The "dB" part indicates it's a decibel measurement (a logarithmic ratio), while the "m" indicates the reference level is one milliwatt (0.001 watts). A power level of 0 dBm equals exactly 1 milliwatt.
The logarithmic nature of dBm makes it ideal for expressing the extremely wide range of power levels encountered in wireless communications, from microwatts to kilowatts. Each 10 dBm increase represents a 10-fold increase in power, while each 3 dBm increase approximately doubles the power. This compressed scale makes calculations and comparisons much more manageable than using linear watts.
The watt (W) is the International System of Units (SI) standard unit of power, representing one joule of energy transferred per second. In electrical and RF systems, watts provide a direct, linear measurement of power. While watts are intuitive for understanding absolute power levels, the extremely wide range of values in RF work (from nanowatts to megawatts) makes linear watt measurements cumbersome.
Converting between dBm and watts allows you to work in whichever unit is most appropriate for your application. dBm is preferred for signal levels, antenna gain calculations, and link budgets, while watts are better for understanding actual power consumption, heating effects, and regulatory compliance limits.
Step-by-Step Conversion Process:
Example Calculation:
Convert 20 dBm to watts
Step 1: 20 - 30 = -10
Step 2: -10 ÷ 10 = -1
Step 3: 10-1 = 0.1 W (or 100 mW)
Alternative Method:
W = 0.001 × 10(dBm/10)
Example: 20 dBm
W = 0.001 × 10(20/10) = 0.001 × 102 = 0.001 × 100 = 0.1 W
Quick Reference Rules:
dBm is the standard unit for expressing transmit power and received signal strength in Wi-Fi, cellular, Bluetooth, and other wireless systems. Converting to watts helps understand actual power consumption and regulatory compliance. For example, Wi-Fi routers typically transmit at 20 dBm (100 mW).
RF engineers use dBm for link budget calculations because logarithmic units allow simple addition and subtraction. However, converting final power levels to watts helps verify components can handle the actual power without damage.
Antenna input power limits and amplifier output ratings may be specified in either dBm or watts. Converting between them ensures you don't exceed component ratings. A 30 dBm amplifier outputs 1 watt maximum.
Spectrum analyzers, power meters, and signal generators typically display measurements in dBm. Converting to watts helps relate measurements to physical power levels and thermal effects. A -10 dBm signal equals 100 microwatts.
Radio transmission regulations often specify limits in both dBm and watts. For example, FCC rules might limit unlicensed transmitters to 30 dBm (1 watt) EIRP. Understanding both units ensures compliance with power limits.
0 dBm equals exactly 1 milliwatt (0.001 watts). This is the reference point for the dBm scale. Positive dBm values represent more than 1 mW, while negative dBm values represent less than 1 mW.
dBm compresses the enormous range of RF power levels into manageable numbers. RF systems deal with powers from picowatts to megawatts - a range of 1018. In dBm, this becomes -90 to +90 dBm, much easier to work with. Additionally, gains and losses can be added/subtracted rather than multiplied/divided.
30 dBm equals exactly 1 watt. This is a key reference point: 0 dBm = 1 mW and 30 dBm = 1 W. Remember that every 10 dBm represents a 10× change in power (0 dBm = 1 mW, 10 dBm = 10 mW, 20 dBm = 100 mW, 30 dBm = 1,000 mW = 1 W).
dBm references milliwatts (0.001 W) while dBW references watts. To convert: dBW = dBm - 30. For example, 30 dBm = 0 dBW (both equal 1 watt). dBW is used for high-power systems like broadcast transmitters.
Yes, negative dBm values represent power levels less than 1 milliwatt. -10 dBm = 0.1 mW (100 µW), -20 dBm = 0.01 mW (10 µW), and so on. Received signal levels in wireless systems are typically negative dBm values.
To convert watts to dBm, use the formula: dBm = 10 × log₁₀(P in watts) + 30. For example, 0.1 watts: dBm = 10 × log₁₀(0.1) + 30 = 10 × (-1) + 30 = 20 dBm. Alternatively: dBm = 10 × log₁₀(P in milliwatts).