Use this electronics calculation for a first-pass component, converter, signal, motor, or sensor estimate when the stated operating conditions and units match the device data.

Measured voltage (V)

Measured or output voltage amplitude.

Reference voltage (V)

Reference or input voltage amplitude.

Compute an amplitude ratio in decibels across equal impedances, dB = 20 * log10(V2 / V1); a tenfold voltage increase is +20 dB. The tool evaluates the supplied inputs together and returns the named outputs below; it does not infer omitted operating conditions or change the units shown.^[1]

Voltage ratio (dB)

Level of the measured voltage relative to the reference.

• Decibels express a ratio; the reference quantity and whether the ratio is power or a field quantity must be explicit. dBm, dBW, dBV, dBu, and dB SPL are not interchangeable, and impedance assumptions matter when converting voltage to power.
• Use finite inputs in the displayed units and preserve more precision than the final presentation requires. Independently verify safety-critical, financial, compliance, or production decisions.

Check the result against the current datasheet and worst-case operating corners, then verify the circuit or measurement with simulation and bench testing where failure matters.

• Decibel Power Ratio Calculator

  Compute a power ratio in decibels, dB = 10 * log10(P2 / P1); a tenfold power increase is +10 dB.

• CMRR dB

  Compute the common-mode rejection ratio in decibels as 20 x log10(differential gain / common mode gain).

• Equalizer Boost Db

  Convert an equalizer's high-frequency-to-reference voltage gain ratio to decibels; both gains must use the same amplitude convention.