dB Unit Converter
Convert between dBFS, dBu, dBV, dBSPL, watts, and volts, or compute an amplitude-ratio or power-ratio dB value directly from two values.
What this tool tells you
What it does
Use this when you need to convert between decibel-referenced units (dBFS, dBu, dBV, dB SPL, watts, volts), or compute a dB value directly from two amplitude or power values.
How to use it
Use the Unit Converter tab for dBu/dBV/dBFS/SPL/watts/volts conversions, or the Amplitude / Power Ratio tab to compute dB from two values, or a resulting value from a reference value and a dB change.
How to interpret it
dB SPL conversions require a calibrated acoustic reference and cannot be derived from voltage alone. Amplitude ratios use 20·log₁₀ and power ratios use 10·log₁₀ — using the wrong one for your quantity gives a result off by a factor of two in the exponent.
Frequently Asked Questions
- What is the difference between dBu and dBV?
- dBu references 0.775V (the voltage across 600Ω that produces 1mW). dBV references 1V. Professional audio uses dBu (+4 dBu standard), consumer audio uses dBV (-10 dBV standard).
- What is dBFS?
- dBFS (decibels relative to Full Scale) is used in digital audio. 0 dBFS is the maximum level before clipping. All values are negative, with typical targets around -14 to -23 dBFS.
- Why is amplitude ratio 20·log₁₀ but power ratio 10·log₁₀?
- Power is proportional to amplitude squared, so doubling amplitude quadruples power. The factor of 2 in the exponent moves from the multiplier (20 vs 10) to keep both scales agreeing at the same physical change — a doubled amplitude is +6.02 dB either way.
- When do I use amplitude ratio vs. power ratio?
- Use amplitude ratio for voltage, sound pressure, or any linear signal quantity. Use power ratio for power, intensity, or energy quantities.
Selected files are processed locally in the browser and are not uploaded to TrueRes for processing. Open this page in a modern browser to use the interactive tool.