dB to Voltage Calculator
Convert decibels to RMS voltage for dBV, dBu, and dBm (with user-specified load impedance). Includes formulas, conversion table, worked examples and a compact FAQ JSON.
decibel to voltage calculator
The conversion of decibels to RMS voltage takes the formula V = V ref 10(dB)/20. Common case: dBV has Vref=1 V, i.e. V ( V) = 10 10 dB V/20 dBu Vref=0.775 V, i.e. V = 0.775 10 dBu V/20. In the case of dBm, it is 10-10 times less times the power (Watts) multiplied by 1000 and then the voltage is obtained as the square root of the product of the power and the load impedance (Omega) which has been previously determined as.
Formula & Table Summary:
- V = V_ref · 10^{dB/20}
- V(dBV) = 10^{dBV/20}
- V(dBu) = 0.775 · 10^{dBu/20}
- P(W) = 10^{dBm/10}/1000; V = √(P·R)
- dBu ≈ dBV + 2.214
Converter Table
| Input | Formula | Output |
|---|---|---|
| dBV | V = 10^{dBV/20} | Vrms (V) |
| dBu | V = 0.775×10^{dBu/20} | Vrms (V) |
| dBm + R | P=10^{dBm/10}/1000; V=√(P·R) | Vrms (V) |
dBm to voltage impedance
To convert decibels (dB) to RMS voltage, to have a reference level: dBV uses a 1 V reference (dBV 0 = 1 V), and both dBu and dBm are power references (dBm 0 = 1 mW) that you can convert to voltage through the load impedance, R. The general formula of voltages based on any dB value is V = Vref x 10(dB)/20. In the case of dBm: transform dBm to watts, i.e,. P = 10dBm/10/1000 and V = sqrt(P x R). These relations provide you with switching between audio pro level, broadcasting specifications, and electrical power units, and are also handy when the designer, audio engineer, or technician wants to be able to read the actual RMS voltage values as a result of decibel values.
db to voltage calculator
Examples
| Scenario | Input | Calc | Result |
|---|---|---|---|
| 0 dBV | 0 dBV | V=10^{0/20} | 1.000 V rms |
| −6 dBV | −6 dBV | V=10^{−6/20} | ≈0.501 V rms |
| 0 dBu | 0 dBu | V=0.775×10^{0/20} | 0.775 V rms |
| 0 dBm into 600Ω | 0 dBm, R=600Ω | P=0.001 W; V=√(0.001×600) | ≈0.775 V rms |
| +3 dBm into 50Ω | +3 dBm, R=50Ω | P≈0.001995 W; V=√(P×50) | ≈0.316 V rms |
Frequently Asked Questions - dB to Voltage Calculator:
How do I convert dBV to volts?
V = 10^{dBV/20} volts (RMS). 0 dBV = 1 V.
How do I convert dBu to volts?
V = 0.775 × 10^{dBu/20} volts (RMS). 0 dBu ≈ 0.775 V.
How do I convert dBm to volts?
First P(W)=10^{dBm/10}/1000, then V = √(P×R) using load impedance R (Ω).
Why does 0 dBm into 600Ω give 0.775 V?
0 dBm = 1 mW; V = √(0.001W × 600Ω) ≈ 0.775 V, same reference as 0 dBu.
How to convert volts to dBV?
dBV = 20·log10(V/1 V) = 20·log10(V).
How to convert volts to dBu?
dBu = 20·log10(V/0.775).
How to convert dBu to dBV?
dBV ≈ dBu − 2.214 (because 20·log10(0.775) ≈ −2.214).
Does dBm to voltage need impedance?
Yes — dBm is a power reference; V depends on the load impedance chosen (e.g., 50Ω, 600Ω).
What is the general dB-to-voltage formula?
V = V_ref × 10^{dB/20}, where V_ref is the voltage reference for that dB unit.
Are these formulas for RMS or peak voltage?
These formulas give RMS voltage. To get peak: V_peak = √2 × V_rms.
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