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Headphone Sensitivity, RMS Voltage & Power Estimate

Estimate nominal headphone power, RMS voltage and current from sensitivity and a modeled sound-pressure level.

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How to use this calculator

  1. Enter the known values in the units shown. Results update as you type.
  2. Where results are editable, change one to solve backwards. Lock a value to hold it fixed.
  3. Use the worked example to check the method. Reset restores the starting fields.

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Formula and method

For an illustrative 100 Ω load rated 85 dB SPL at 1 mW, a modeled level of 75 dB SPL requires 0.1 mW, 0.1 V RMS and 1 mA RMS. This is a nominal electrical estimate, not a measured listening level.

P(mW) = 10^[(L − S₁mW)/10]; Vᵣₘₛ = √[P(mW)R/1,000]; Iᵣₘₛ = Vᵣₘₛ/R; S₁mW = S₁V + 10 log₁₀(R/1,000)

Worked example

Enter these known values and leave the other values blank.

Nominal headphone load impedance
100 Ω
Sensitivity: dB SPL at 1 mW
85 dBSPL
Modeled sound-pressure level
75 dBSPL
Sensitivity: dB SPL at 1 V RMS
95 dBSPL
Estimated average electrical power
0.1 mW
Estimated RMS voltage
0.1 V
Estimated RMS current
1 mA
One-eighth impedance reference (R/8)
13 Ω

Assumptions and limitations

  • The model treats the nominal impedance as a resistive load and assumes the supplied sensitivity applies at the same test frequency and measurement conditions. Actual headphone impedance and response vary with frequency.
  • Sensitivity per milliwatt and sensitivity per volt are different specifications. Enter the convention stated by the manufacturer; the calculator converts between them using the nominal load.
  • Power, voltage and current are forward outputs. This does not assess an amplifier’s available voltage/current, distortion, clipping, gain or musical peak headroom.
  • The R/8 output is an illustrative one-eighth impedance heuristic retained from the source. It is not a universal compatibility requirement, an amplifier load rating or a safety limit.
  • The retained input ceiling of 120 dB SPL is a numerical bound, not a safe listening recommendation. This model cannot measure ear-level exposure or determine safe listening duration; duration, actual sound level and measurement weighting matter.

Common questions

Can I treat the result as a measured listening volume?

No. Nominal sensitivity and impedance do not measure the sound at your ear, fit, music spectrum or exposure over time. The result is an electrical model estimate.

Why does dB per volt differ from dB per milliwatt?

One volt supplies different power into different load impedances. The logarithmic conversion accounts for that power difference under the resistive-load assumption.

References

The calculation equations, inverse formulas, units, and input rules were imported from this source. Bookify provides the interface and equation solver.

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