Bench tool

dB / Voltage / Power Ratio Calculator

Type a value into any one field — the other two convert automatically.

Decibels (dB) solved

Voltage ratio (V₂/V₁) solved

Power ratio (P₂/P₁) solved

Assumes voltage ratio and power ratio are measured across the same impedance. Clear a field and type a different one to switch which value drives the conversion.

dB = 20 × log₁₀(voltage ratio)

dB = 10 × log₁₀(power ratio)

voltage ratio = 10^(dB / 20)

power ratio = 10^(dB / 10)

Negative dB values give ratios below 1 (attenuation); positive dB values give ratios above 1 (gain). This is a relative-ratio conversion — for absolute levels like dBV (referenced to 1V) or dBm (referenced to 1mW into a defined impedance), the reference value needs to be specified separately.