Abstract: A formula used for estimation energy released from large explosion in atmosphere by using infrasound is presented. By taking approximations in the sound pressure formula, we obtained a very simple form: Y=CPTR^1/2;Y is the energy, the unit is erg; C is a constant, its value is 8x10¹⁸; P is the average value of the first three peak-peak pressure amplitudes of the infrasonic wave trains, in μb; T is average period in sec; R is the distance between source and observation station, the unit is Mm. Through a lot of tests, the accuracy of this method is about 100%. Otherwise, this method have some advantages. For example, the formula is not sensitive to the meteoric condition due to using the average value.
Based on this formula, we can estimate the energy released from the meteorite fall explosion on 30 June, 1908. in Central Siberia as 2.3x10^-24 erg.