The internal luminescence quantum efficiency (Q_i^lum) provides an excellent assessment of the optoelectronic quality of semiconductors. To determine Q_i^lum from the experimentally accessible external luminescence quantum efficiency (Q_e^lum), it is essential to account for photon recycling, and this requires knowledge of the photon escape probability (p¯_e). Here, we establish an analysis procedure based on a curve-fitting model that accurately determines p¯_e of perovskite films from photoluminescence (PL) spectra measured with a confocal microscope and an integrating sphere setup. We show that scattering-induced outcoupling of initially trapped PL explains commonly observed red-shifted and broadened PL spectral shapes and leads to p¯_e being more than a factor of two higher compared with earlier assumptions. Applying our model to CH₃NH₃PbI₃ films with exceptionally high Q_e^lum up to 47.4% corrects previous estimates for Q_i^lum of ∼90% to a real benchmark of 78.0% ± 0.5%. Thereby, our study reveals there is beyond a factor of two more scope for reducing non-radiative recombination in perovskite films than previously thought.