Signal Attenuation Calculator

Work out signal attenuation instantly with clear inputs, formula shown and shareable results.

About Signal Attenuation Calculator

Attenuation in decibels adds along a chain, which is the whole point of working in dB. Every 3 dB halves the power and every 10 dB divides it by ten, so three 6 dB stages give 18 dB total — a factor of about 63 reduction in power.

Formula

Attenuation

Pout(dBm) = Pin(dBm) - total dB; power ratio = 10^(-dB/10)

Worked example

With the default values below, Signal Attenuation Calculator returns Output power of -8.00. Change any input above and every figure here is recalculated in your browser.

Inputs used

Input power: 10 dBm
Attenuation: 6 dB
Number of identical stages: 3 stages

Results

Output power: -8.00 dBm
Total attenuation: 18.00 dB
Output as fraction of input: 0.015849
Output power: 0.15849 mW

Step by step

1Values used
2Attenuation
3Output power= -8.00 dBm
4Total attenuation= 18.00 dB
5Output as fraction of input= 0.015849
6Output power= 0.15849 mW

Assumptions and limits

The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 6 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

Why work in decibels?

Because cascaded gains and losses simply add instead of multiplying, and the logarithmic scale spans the enormous dynamic range of RF systems compactly.

What does dBm mean?

Power referenced to one milliwatt: 0 dBm is 1 mW, 30 dBm is 1 W, and -100 dBm is a typical weak receive signal.