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.
About this calculator
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.