Amplifier Watts Needed (SPL)

Work out how many amplifier watts you need to reach a target volume at your listening distance from speaker sensitivity, free online.

Speaker sensitivity (dB @ 1 W, 1 m)

Target average volume at your seat (dB SPL)

Listening distance (m)

Headroom for peaks (dB)

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SPL at distance d from a speaker driven with P watts is: SPL = sensitivity (dB @ 1 W/1 m) + 10·log₁₀(P) − 20·log₁₀(d). Solving for P gives the power needed. Add 3–6 dB of headroom for dynamic peaks, which doubles or quadruples the watts.