Abstract Histotripsy is an emerging ultrasound technology for disintegrating various soft tissues noninvasively and accureately. However, it is difficult to characterize the acoustic field of a histotripter using the existing measurement methods (i.e., hydrophones) because of the damage potential of bubble cavitation on the sensing element under such high irradiation power. In this work, according to a quantitative relationship between the acoustic pressure and ultrasonic focusing gain G, nonlinearity β, attenuation coefficient α, a numerical reconstruction method is proposed to accurately and reliably estimate the acoustic field of a histotripter. The k-Wave toolbox was used to calculate the acoustic field produced from identical sectors on a common concave surface by gradually increasing the number of excitation elements (i.e., up to 256 that cover the whole surface). The excitation frequency is 0.8 MHz, and the initial pressure at the transducer surface is 0.4 MPa. The focusing gains, peak positive and negative pressure, positive to negative peak acoustic pressure ratio, and harmonic distributions in the focal region under different numbers of excited elements were analysed. It is found that when about a quarter of the transducer surface is excited (64 elements), the nonlinear effect becomes obvious, resulting in significant peak pressures and harmonics. Furthermore, the relationship between the positive and negative pressure peaks (p + and p ¬) and the number of excited elements fits a quadratic curve function quite well (R = 0.999). Altogether, the proposed method can be applied to estimate the acoustic pressure at an extremely high intensity that exceeds the range of current measurement apparatus. Acoustic pressures using a low number of excited elements are measured first and then extrapolated to the full surface coverage using the built-in regression models. In the near future, the field calculation scheme for the therapeutic focused transducers with higher irradiation power and larger dimensions, as well as experimental work, will be done to further validate our model.