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Instant Calculation
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Cable losses, attenuator pads, and filter specs are often given as a single dB attenuation figure — this tool converts that figure directly into the resulting power and voltage/amplitude ratios, so you can see concretely how much signal is actually lost.
How it works
Enter the attenuation in dB, and the calculator applies the inverse of the standard decibel formulas: power ratio = 10^(−dB/10), voltage ratio = 10^(−dB/20).
- Enter attenuation (dB).
- Click Calculate to see your results.
Examples
A common attenuator rating
A 20 dB attenuator reduces voltage/amplitude to 10% and power to just 1% of the original — a good number to remember, since every additional 20 dB divides voltage by another factor of 10.
Who should use it
- Estimating real signal loss from a cable or attenuator's dB rating.
- RF and audio system design and troubleshooting.
Industry applications
- RF and telecommunications engineering
- Audio engineering and system design
Advantages
- Directly converts a spec-sheet dB figure into concrete, intuitive ratios.
- Shows both power and voltage ratios together.
Limitations
- Assumes the dB figure you have is already scaled correctly for your actual scenario (length, frequency, etc.).
Common mistakes to avoid
- Using a cable's per-unit-length dB rating directly without scaling it to your actual cable length first.
- Confusing power ratio with voltage ratio — they're both "ratios" but represent different physical quantities.
Best practices
- Scale a per-length attenuation spec (e.g. dB per 100 ft) to your actual cable length before entering it here.
- Use the voltage ratio when reasoning about signal amplitude, and the power ratio when reasoning about actual signal power/energy.
Tips
- Remember every 20 dB of attenuation divides voltage by another factor of 10 — a handy mental shortcut for quick estimates (20 dB → 10%, 40 dB → 1%, 60 dB → 0.1%, and so on).