What is the difference between dBu and dBV?

dBu uses a reference voltage of 0.7746V (the voltage that produces 1 mW across 600 ohms). dBV uses a reference of 1V. 0 dBu = -2.2 dBV. Professional equipment typically operates at +4 dBu (1.228V), while consumer gear uses -10 dBV (0.316V).

What is dBFS and how does it relate to dBu?

dBFS (decibels relative to full scale) is the digital audio scale where 0 dBFS is the maximum level before clipping. The relationship to dBu depends on the converter's headroom setting — typically +18 dBu or +24 dBu corresponds to 0 dBFS.

dBm is a power measurement referenced to 1 milliwatt. It is commonly used in RF and telecommunications. 0 dBm = 1 mW. In audio, dBm was historically used with 600-ohm systems but has largely been replaced by dBu.

Why is +4 dBu the professional standard?

+4 dBu (approximately 1.228V RMS) was chosen as the professional operating level because it provides a good balance between headroom and signal-to-noise ratio in analogue equipment. It sits well above the noise floor while leaving sufficient headroom before clipping.

AudioCalcs

dB Conversion Calculator — dBu, dBV, dBFS, dBm & Voltage

Convert between dBu, dBV, dBFS, dBm and voltage/power values used in professional and consumer audio.

Conversion Mode

Input Value

How We Calculate This

dBu to Voltage

V = 0.7746 × 10^(dBu/20)

Voltage to dBu

dBu = 20 × log10(V / 0.7746)

dBV to Voltage

V = 1.0 × 10^(dBV/20)

dBFS to dBu

dBu = dBFS + headroom (where headroom is the dBu value corresponding to 0 dBFS)

dBm to Watts

W = 10^(dBm/10) / 1000

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Last updated: February 2026

All calculations are estimates based on standard formulas. Always verify results for critical applications.