A decibel (dB) is a logarithmic unit used to express the ratio of two values, most commonly sound pressure or power. Because human hearing spans roughly a 10-trillion-fold range of intensity, the logarithmic scale makes it manageable.

What is the difference between amplitude and power ratios?

Power and intensity ratios use dB = 10 log10(P2/P1). Amplitude or sound-pressure ratios use dB = 20 log10(A2/A1) because power is proportional to amplitude squared.

How much louder is 10 dB than 0 dB?

A 10 dB increase corresponds to a 10-fold increase in sound power/intensity ratio (10^1 = 10). Perceptually, humans generally perceive a 10 dB increase as roughly twice as loud.

Does doubling the sound power add 3 dB or 6 dB?

Doubling the power adds approximately 3 dB (10 log10(2) ≈ 3.01 dB). Doubling the amplitude (pressure) adds approximately 6 dB (20 log10(2) ≈ 6.02 dB).

0 dB does not mean silence. It means the measured level equals the reference level (ratio = 1). The standard reference for sound pressure level (SPL) in air is 20 micropascals, roughly the threshold of human hearing.

Can dB values be negative?

Yes. A negative dB value means the measured quantity is below the reference level (ratio < 1). For example, a level 10 dB below the reference is -10 dB.

What does 44 decibels sound like?

About 44 dB is a quiet indoor sound — between a soft whisper (~30 dB) and a normal conversation (~60 dB). It is close to the level of a quiet library, light rain, or a refrigerator humming a few feet away, and is generally considered comfortable for sleep and concentration.

Decibel Calculator

Convert between decibels, amplitude or sound-pressure ratios, and power ratios.

Conversion Mode

Select what you know, enter the value, and get all related quantities.

Decibel value (dB)

Results

Enter a value and click Calculate.

Common Sound Levels

Source	Level (dB)

Summary

Convert between decibels, amplitude or sound-pressure ratios, and power ratios.

How it works

Choose a conversion mode: dB to ratio, amplitude ratio to dB, or power ratio to dB.
Enter the known value in the input field.
Click Calculate (or press Enter) to see all related values.
Use the reference table at the bottom to understand real-world dB levels.
Clear the inputs with the Reset button and try another value.

Use cases

Convert a measured dB level to a physical intensity ratio.
Determine how many decibels correspond to doubling the sound power.
Understand the logarithmic scale of everyday sounds.
Check amplifier gain expressed in dB against a linear power ratio.
Compare two sound sources and find the dB difference.
Quickly look up the dB level of common noise sources.

Frequently Asked Questions

Last updated: 2026-09-22 · Reviewed by Nham Vu