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Rojony Khatun
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Last updated: October 1, 2025

dB to Voltage Calculator | dBV, dBu & dBm Conversions

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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

InputFormulaOutput
dBVV = 10^{dBV/20}Vrms (V)
dBuV = 0.775×10^{dBu/20}Vrms (V)
dBm + RP=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

ScenarioInputCalcResult
0 dBV0 dBVV=10^{0/20}1.000 V rms
−6 dBV−6 dBVV=10^{−6/20}≈0.501 V rms
0 dBu0 dBuV=0.775×10^{0/20}0.775 V rms
0 dBm into 600Ω0 dBm, R=600ΩP=0.001 W; V=√(0.001×600)≈0.775 V rms
+3 dBm into 50Ω+3 dBm, R=50ΩP≈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.

Rojony Khatun

Rojony Khatun

CalculatorToolsProject

Rojony Khatun is the creator of a free online tools website designed to simplify everyday and engineering-related calculations for students, professionals, and hobbyists. The platform offers a wide variety of basic and advanced calculators across key categories, including Electrical Calculators, Electronic Calculators, and Time & Date Calculators, helping users solve problems quickly and accurately.