Headphone Power Calculator

Sensitivity measures how efficiently your headphones convert electrical power into sound, expressed as dB SPL per milliwatt (dB/mW) or per volt (dB/V). Higher sensitivity means louder output for the same amount of power. Headphones with low sensitivity (e.g. 85 dB/mW) need significantly more power than high-sensitivity models (e.g. 110 dB/mW) to reach the same volume.

Impedance is the electrical resistance of your headphones, measured in ohms (Ω). High-impedance headphones (150–600 Ω) typically require more voltage to drive properly, while low-impedance models (16–32 Ω) need more current. Matching your headphone's impedance to an appropriate amplifier output impedance ensures the best sound quality and frequency response.

dB/mW measures sensitivity relative to one milliwatt of input power, while dB/V measures it relative to one volt. The relationship between them depends on impedance: dB/V = dB/mW + 10 × log10(impedance / 1000). Many higher-impedance headphones use dB/V ratings. This calculator handles both units and converts between them automatically.

For safe long-term listening, 85 dB SPL is the recommended limit by health authorities. A target of 100–110 dB is useful to ensure your amplifier has enough headroom for dynamic music peaks without distortion. Setting 110–120 dB lets you calculate the amp's maximum power requirement, even if you never actually listen that loud.

Music has dynamic peaks that can exceed the average listening level by 6–20 dB. Without headroom, your amplifier clips during loud transients, causing distortion. A good rule of thumb is to choose an amplifier that can deliver at least 4× (6 dB) to 10× (10 dB) the calculated minimum power at your target loudness.

Most smartphones and laptops output between 1–30 mW into a 32 Ω load. They work fine with sensitive, low-impedance headphones (e.g. sensitivity ≥ 100 dB/mW, impedance ≤ 32 Ω). However, planar magnetics, high-impedance dynamics (250–600 Ω), or low-sensitivity studio headphones almost always need a dedicated headphone amplifier or DAC/amp combo.

Electrostatic headphones use a different transducer technology that requires a high-voltage energizer (bias voltage of 230–580V) rather than a conventional current/voltage amplifier. They cannot be driven by standard headphone amplifiers at all. If you own electrostatic headphones, you need a dedicated electrostatic amplifier (energizer).

Check the product page on the manufacturer's website, the included user manual, or the headphone's packaging. Sensitivity is typically listed as a number like '103 dB/mW' or '110 dB/V', and impedance as '32 Ω' or '250 ohms'. Audio databases like Rtings.com and the manufacturer's spec sheet are reliable sources if you can't find them in the box.