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What does this calculator estimate?
A +6 dB power change multiplies power by 10^(6/10) = about 3.98, a roughly 298 percent increase. The same +6 dB in amplitude multiplies by 10^(6/20) = about 2.0, a 100 percent increase.
- Power ratio = 10^(dB / 10); amplitude ratio = 10^(dB / 20).
- +10 dB is a 10x power change; +20 dB is a 100x power change.
- Decibels are logarithmic, so equal dB steps are equal ratios.
What decibels mean
The decibel is a logarithmic ratio — it compresses huge power differences into usable numbers. +10 dB means 10× the power; +3 dB means 2×. It's used in audio, RF, and acoustics because human perception is roughly logarithmic.
Limitations to watch for
Power and amplitude use different formulas — confusing them gives wrong results. The tool reports the ratio for the type you choose. dB without a reference (dBm, dBu, dB SPL) is just a ratio, not an absolute level.
How to use it in practice
Use it to interpret audio gain stages, speaker specs, and filter slopes. Remember the key points: +3 dB = 2× power, +6 dB = 4× power, +10 dB = 10× power, −3 dB = half power (the common 'cutoff' point).
['Enter the dB change (positive or negative).', 'Choose power or amplitude.', 'The tool reports the ratio and percent change.']
How this calculator works
Formula
Power ratio = 10^(dB ÷ 10). Amplitude ratio = 10^(dB ÷ 20). Percent change = (ratio − 1) × 100. Every +10 dB is a 10× power increase; +20 dB is a 10× amplitude increase.
Worked example
+10 dB (power) = 10× louder; +20 dB (amplitude) = 10× the amplitude. −6 dB (power) ≈ 25% of original power.
Assumptions to verify
- The dB value is a ratio, not an absolute level.
- The chosen type (power or amplitude) matches the measurement.
- Standard logarithmic conversion is used.
Frequently asked questions
How do I convert dB to a ratio?
For power: 10^(dB/10). For amplitude: 10^(dB/20). +10 dB power = 10×, +20 dB amplitude = 10×.
Why are there two formulas?
Power scales with the square of amplitude, so the same dB change represents different ratios for power vs amplitude.
How loud is +3 dB?
About 2× the power — commonly the smallest change most listeners notice. +10 dB is perceived as roughly twice as loud.
What is dB SPL?
Decibels relative to the threshold of hearing (20 µPa) — the absolute sound-pressure scale used in acoustics.
What are dBm and dBu?
dBm references 1 milliwatt (RF power); dBu references 0.775 V (audio voltage). Without a reference, dB is just a ratio.
How does this apply to filters?
A −3 dB point is the standard cutoff: the frequency where output power halves.
Can dB be negative?
Yes — negative dB means a reduction: −6 dB power ≈ 25% of the original.
Cite this tool
BoringToolsKit. “dB to Volume Ratio Calculator.” boringtoolskit.com/db-to-volume-calculator/ (reviewed 2026-08-25). Free to reference in articles, syllabi, and answer posts with a link.
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