When NMR signal amplitudes achieved from spin-echo sequences with several different repetition times are used to calculate T1, this can be done rapidly by calculating the time coordinate of the center of gravity of the data and determining which T1 should theoretically give this value. In particular, when a large number of similar calculations are made, the time gain may be massive. Simulations suggested that this procedure is only slightly less accurate than least-squares fitting, and far more rapid. The procedure may also be useful in other types of T1 determination.