The probability density function of the temperature autocorrelation is given in a semi-analytical form for the case of Gaussian temperature fluctuations. Based on this result we obtain confidence intervals for the anisotropies expected in several cosmological scenarios dominated by baryonic (B), hot dark matter (HDM) and cold dark matter (CDM) with adiabatic fluctuations. We also confront these expectations with the upper limits given by the present experiments at large angular scales.