About

Acoustics and telecommunications engineering rely heavily on logarithmic scales to manage the vast dynamic range of human hearing and signal strength. This converter addresses the most frequent source of calculation error in the field: the distinction between Power quantities (Watts) and Field/Root-Power quantities (Volts, Amperes, Pressure). Using the wrong logarithmic multiplier-10 versus 20-results in a doubling or halving error in the final Decibel (dB) reading.

This tool is designed for technicians aligning gain stages, calibrating microphones, or calculating path loss. It includes a dynamic visualization of Sound Pressure Levels (SPL) to provide immediate context, helping users relate abstract numbers to physical realities like the silence of a recording studio or the threshold of pain in a live concert environment. The system automatically handles the logarithmic math, ensuring precision for system integration.

Formulas

The calculation depends entirely on whether the physical quantity being measured is Power (energy per time) or a Field quantity (amplitude). The Decibel is a dimensionless ratio of the measured value to a reference value.

{

L_dB = 10 ⋅ log₁₀P₁P₀ for PowerL_dB = 20 ⋅ log₁₀V₁V₀ for Voltage/Pressure

Where P represents power (Watts) and V represents voltage, current, or sound pressure.

Reference Data

Reference Level	Value	Application	Formula Mode
0 dBm	1 mW	Radio/Audio Power	10 log
0 dBu	0.775 V	Pro Audio (Analog)	20 log
0 dBV	1.0 V	Consumer Audio	20 log
0 dBFS	Max Digital Level	Digital Audio	20 log
0 SPL	20 µPa	Acoustics Threshold	20 log
+4 dBu	1.228 V	Pro Line Level	20 log
-10 dBV	0.316 V	Consumer Line Level	20 log
60 dB SPL	Conversation	Environmental	-
120 dB SPL	Jet Engine	Threshold of Pain	-

Frequently Asked Questions

Use the "20 log" rule whenever you are measuring quantities that are squared to calculate power. This includes Voltage (Volts), Current (Amperes), and Sound Pressure (Pascals). This is common in voltage gain calculations and microphone sensitivity.

Use the "10 log" rule strictly for Power quantities measured in Watts. This is common in RF engineering (dBm) and amplifier output specifications.

Both measure voltage, but their reference points differ. 0 dBu references 0.775 Volts (derived from 600-ohm telephony standards), while 0 dBV references exactly 1.0 Volt. This difference means 0 dBV is louder than 0 dBu by approximately 2.2 dB.

In terms of Power, a +3 dB change represents a doubling of power (x2). In terms of Voltage, a +6 dB change is required to double the voltage.