1. What is dBm?

dBm (decibels-milliwatts) is a unit of power measurement that expresses absolute power in decibels relative to 1 milliwatt. It's commonly used in radio, microwave, and fiber-optic communication networks.

2. Conversion Formula

The formula to convert watts to dBm is:

Where:

• \( W \) — Power in watts
• 1000 — Conversion factor (1 watt = 1000 milliwatts)
• \( \log_{10} \) — Base-10 logarithm

Explanation: Since dBm is referenced to 1 milliwatt, we first convert watts to milliwatts by multiplying by 1000, then take the base-10 logarithm and multiply by 10 to convert to decibels.

3. Practical Applications

Details: dBm is widely used in telecommunications to express signal strength. Common values range from -120 dBm (very weak signal) to +30 dBm (very strong signal). Most wireless networks operate between -70 dBm (good) and -90 dBm (poor).

4. Using the Calculator

Tips: Enter power in watts (W). The value must be positive. For example, 0.001 W (1 mW) = 0 dBm, 1 W = 30 dBm, 10 W = 40 dBm.

5. Frequently Asked Questions (FAQ)

Q1: Why use dBm instead of watts?
A: dBm provides a logarithmic scale that makes it easier to work with very large and very small power levels common in communications.

Q2: What is 0 dBm in watts?
A: 0 dBm equals exactly 1 milliwatt (0.001 W), which is the reference power level for dBm measurements.

Q3: How does dBm relate to dB?
A: dB is a relative unit (ratio), while dBm is absolute (referenced to 1 mW). A 3 dB increase means doubling the power.

Q4: What are typical dBm values in WiFi?
A: Excellent: -30 dBm to -50 dBm, Good: -50 dBm to -65 dBm, Fair: -65 dBm to -80 dBm, Poor: -80 dBm or below.

Q5: Can dBm be negative?
A: Yes, negative dBm values represent power levels less than 1 mW. For example, -30 dBm = 0.001 mW = 1 μW.