The fast Hartley transform (FHT) is emerging as an alternative to the more popular fast Fourier transform (FFT) in the processing of real signals. In this paper, a fixed-point error analysis has been carried out. The basic differences between the FFT and FHT flowcharts from the point of view of error analysis are first discussed. A suitable scaling model is chosen for the FHT and the average output signal-to-noise ratio is calculated both for decimation-in-frequency and decimation-in-time cases. The results are then compared with the FFT error-analysis results. © 1990.