Headphone Power & Amp Requirement Calculator
Voltage, current and power a headphone needs for a target loudness from its impedance and sensitivity (dB/mW or dB/V) — does your phone, DAC dongle or amp have enough headroom?
How it works
P (mW) = 10^((SPL − sensitivity dB/mW) ÷ 10); V = √(P × Z); I = V ÷ Z; dB/mW = dB/V − 10·log₁₀(1000 ÷ Z)
How loud a headphone plays depends on its sensitivity — decibels produced per milliwatt or per volt — and the power its source can supply into its impedance. Every 10 dB more SPL needs ten times the power, so the difference between 100 dB and 110 dB peaks is a full order of magnitude. High-impedance studio headphones (250–600 Ω) need voltage: a phone’s one-volt output manages only a few milliwatts into 300 Ω and may top out below comfortable peak levels, while a desktop amp with 5–7 V has ample headroom. Very sensitive low-impedance in-ears have the opposite problem — hiss and a source output impedance that alters their frequency response (keep it below an eighth of the headphone impedance). Around 110 dB of peak capability is a sensible target for dynamic music at safe average levels.
Worked example
300 Ω, 102 dB/mW headphones for 110 dB peaks: 6.3 mW, 1.37 V rms, 4.6 mA. A 2 V dongle reaches 113 dB — 3 dB of headroom; a 1 V phone jack tops out at 107 dB.
Frequently asked questions
Is more power always better?
Beyond adequate headroom, no — but an amp with 10× the needed power is not harmful; the volume knob sets the level. Very powerful amps can make sensitive IEMs hiss or have coarse volume steps.
What about balanced outputs?
Balanced (4.4 mm / XLR) outputs typically double the voltage of the single-ended jack, adding 6 dB of headroom — useful for high-impedance or planar headphones.
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This calculator is for educational purposes. Double-check important results before acting on them.