dBu to Volts RMS Converter

dBu states an audio voltage relative to 0.7746 volts RMS, and this converter runs the definition backwards: V equals 0.7746 times 10 raised to (dBu/20). The reference is not arbitrary — it is the voltage that dissipates exactly 1 mW into a 600-ohm load, inherited from telephony and the older dBm unit. The 'u' stands for unloaded (or unterminated): unlike dBm, dBu describes voltage alone and holds for any impedance, which matches how modern gear actually interconnects, with low-impedance outputs driving high-impedance bridging inputs.

The everyday case is professional line level: enter 4 and the tool returns 1.227658 V, the +4 dBu nominal level that consoles and audio interfaces are calibrated around. Other useful anchors: 0 dBu gives 0.7746 V, minus 20 dBu gives 77.46 mV, and minus 60 dBu — the ballpark of a microphone signal — yields 0.0007746 V, shown as 7.7460e-4 because anything below 0.001 switches to scientific notation. The constant in the code is 0.7746, a rounding of the exact square root of 0.6 (0.774597 V); the discrepancy is about 3 microvolts at 0 dBu, meaningless for any audio purpose.

Scope matters: the page converts dBu to volts only, through a single field. It does not go the other way (for that, dBu equals 20 times log10 of the voltage over 0.7746), it does not handle dBV — whose 1 V reference sits 2.218 dB above dBu — and it cannot compute dBm, which would require knowing the load impedance. It also says nothing about digital headroom: mapping +4 dBu to dBFS depends on converter calibration (commonly +4 dBu lands at minus 18 or minus 20 dBFS under EBU or SMPTE practice), which is outside this arithmetic. An empty field is treated as 0 dBu and shows 0.7746 V.