Error propagation equations are derived for four different sound-power measurement techniques: hemispherical freefield, reference source, reverberation time, and two surface. The analysis shows the hemispherical freefield and two-surface methods to be governed by the same error equation. Of the four methods examined, the reference-source method is shown to exhibit the strongest dependence on errors in measuring the space averaged sound pressure. The results obtained can be used in planning and executing more accurate sound-power measurements.