dB / Level Converter
Convert between dBu, dBV, dBFS, volts, watts. Combine multiple sources with the add-dB feature. Professional reference levels included.
dB Converter
All Conversions
Add dB Values (Combine Sources)
Enter multiple dB values to calculate their combined level. Useful for summing speaker outputs, multiple mics, or any coherent/incoherent sources.
Formula: Combined = 10 × log10(Σ 10^(dBᵢ/10)). Assumes incoherent (uncorrelated) sources. For coherent in-phase sources, add 6 dB per doubling instead of 3 dB.
Professional Reference Levels
| Standard | Level | Voltage | Typical Use |
|---|---|---|---|
| Professional line level | +4 dBu | 1.228 V | Studio, live sound, broadcast |
| Consumer line level | -10 dBV | 0.316 V | Hi-fi, consumer gear |
| Microphone level | -60 to -40 dBu | 0.001–0.008 V | Dynamic/condenser mics |
| Instrument level | -20 to -10 dBu | 0.078–0.245 V | Guitars, keyboards (passive) |
| Digital full scale | 0 dBFS | — | Maximum digital level |
| EBU / Professional recording | -18 dBFS | — | 0 dBu = -18 dBFS |
| SMPTE / Post production | -20 dBFS | — | 0 dBu = -20 dBFS |
| Headroom target (peaks) | -12 to -6 dBFS | — | Leave room for transients |
Why It Matters
dBu = dBV + 2.218
dBV = dBu - 2.218
dBu = 20 × log10(Volts / 0.775)
Volts = 0.775 × 10^(dBu/20)
Watts (600Ω) = Volts² / 600
dBu = 10 × log10(Watts × 600 / 0.775²)Frequently Asked Questions
What's the difference between dBu and dBV?
dBu references 0.775V (the voltage that delivers 1mW into 600Ω). dBV references 1V. The difference is always 2.218 dB. Professional gear uses dBu; consumer gear uses dBV. +4 dBu = -1.78 dBV.
Why does 0 dBFS map to different analog levels?
Digital full scale (0 dBFS) is fixed, but the analog level it represents varies by convention. EBU R68 sets 0 dBu = -18 dBFS (broadcast standard). SMPTE sets 0 dBu = -20 dBFS (post-production). Yamaha CL/QL uses -20 dBFS. The converter lets you choose the reference that matches your console.
When do I use "Add dB" vs just adding voltages?
Add dB (this tool) = incoherent sources (different mics, separate speakers, uncorrelated noise). Formula: 10×log10(Σ10^(dB/10)).
Voltage addition = coherent in-phase sources (same signal to multiple amps). Then 2× voltage = +6 dB, not +3 dB. This tool assumes incoherent — standard for live sound.
What does -18 dBFS = +4 dBu actually mean?
It's a calibration point. When your console meter reads -18 dBFS, the analog output is +4 dBu (1.228V). This gives 18 dB of headroom before digital clipping (0 dBFS). At +4 dBu nominal, peaks can reach +22 dBu before clipping the converter — plenty for transients.
Can I convert speaker sensitivity (dB SPL @ 1W/1m) to watts?
Speaker sensitivity is SPL, not electrical level. This tool converts electrical levels only. For SPL calculations, you need: SPL = Sensitivity + 10×log10(Watts) - 20×log10(Distance). That's a different calculator (PA coverage tool coming later).
Recommended SPL Meters & Level Testers
Tools for verifying levels in the field:
- NTi Audio XL2 — professional analyzer, Class 1
- NTi Audio MiniSPL — compact, Class 2, phone app
- Behringer ECM8000 + UMIK-1 — budget measurement mic + REW
- Casella CEL-63X — logging dosimeter for noise compliance
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