A study is presented on the assessment of the Fe2+concentration in Fe‐doped InP by the quantitative evaluation of the Fe2+intracenter absorption at 2800–3200 cm−1. Based on a comparison with secondary‐ion mass spectrometry data fromn‐type samples, a calibration factor is derived for the oscillator strength of the zero‐phonon lines at 10 K. The detection limit for 500 &mgr;m samples is ≊5×1013cm−3.