dB ↔ Ratio Converter (Power/Voltage)
Convert dB to power ratio and voltage (field) ratio, and back. 20 dB = 10× voltage, 100× power.
Worked example
Decibel 20 dB, Power ratio 100 ×, Voltage (field) ratio 10 ×
Formula
Power ratio = 10^(dB/10)
Voltage ratio = 10^(dB/20)
How it works
The same dB value means different ratios for power and for voltage. Power uses 10·log₁₀, while voltage, field and current use 20·log₁₀, so 20 dB is a 10× voltage ratio and a 100× power ratio. Handy when translating shielding effectiveness or insertion loss into plain multiples.
Practical tipMental-math anchors: 3 dB ≈ 2× power, 6 dB ≈ 2× voltage, 10 dB = 10× power, 20 dB = 10× voltage, 40 dB = 100× voltage, 60 dB = 1000× voltage.
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Results and summaries are for reference. For certification and test reports use the latest official standard text and calibrated instrument data. Last updated: 2026-10-10