Headphone power calculator
Estimated SPL and required RMS voltage/current from sensitivity at 1 mW.
Fill in the fields and the result will appear here automatically.
Estimate SPL from sensitivity specified at 1 mW, then compare the required RMS voltage and current with an amplifier specification. Sensitivity belongs to stated acoustic test conditions. Nominal impedance is treated as a resistance here; real headphone impedance varies with frequency. This is not a sound measurement at the ear or an exposure-time assessment.
How it works
Formula and logic
SPL=S₁mW+10·log₁₀(PmW/1 mW). The electrical calculation uses PW=PmW/1000: U_RMS=√(PW·R), I_RMS=√(PW/R). Sensitivity may be any finite dB level; R and P must be positive. A decibel level is not a linear power input. The acoustic estimate additionally assumes a linear response: under matching conditions, sound intensity is proportional to applied electrical power.
Example
S=100 dB at 1 mW, R=32 Ω and P=10 mW give 110 dB, 0.5657 V RMS and 17.678 mA RMS. At 1 mW the level equals S and the gain is 0 dB. Zero power has no finite logarithmic level and is outside this mode.
Fields and units
- Sensitivity at 1 mW — dB
- Nominal impedance (resistive model) — Ω
- Applied power — mW
How to use
- — Use sensitivity with an explicit 1 mW reference and stated test conditions.
- — Convert a 1 V sensitivity using impedance before entering it; dB/V and dB/mW are different references.
- — Enter power in mW and resistance in Ω; electrical results are RMS under the resistive model.
- — The tool defines neither comfortable nor safe levels and does not account for fit, programme, duration or distortion.
Method and limitations
- Calculation method
- Formula and logic
- Data or methodology source
- OpenStax: logarithmic levels and intensity ratios OpenStax: RMS and active power with cosφ
- Limitation
- Sensitivity-based estimate and resistive RMS model; not measured ear SPL or hearing-protection guidance.
FAQ
Why does twice the power add about 3 dB?
10·log₁₀2=3.0103 dB; a 10 dB increase requires ten times the power. These are level differences, not universal rules for perceived loudness.
Which matters more, impedance or sensitivity?
At equal sensitivity referenced to 1 mW, equal power gives equal estimated SPL under matching test conditions. Voltage rises with √R while current falls with √R.
How do I compare the estimate with an amplifier?
Compare the calculated RMS voltage and current with source limits at that impedance, including clipping and rated loading. The tool does not determine distortion, headroom or a need to buy a separate amplifier.
Why are dB/mW and dB/V different?
For the resistive model S₁mW=S₁V−10·log₁₀(1000/R). The difference is 14.9485 dB at 32 Ω and 5.2288 dB at 300 Ω; both specifications must use matching acoustic test conditions.