Abstract: An ultrasound device and method for calculating an estimated tissue stiffness based on peak on-axis tissue displacement propagating along the axis of an acoustic radiation force (ARF) excitation region are disclosed. Embodiments estimate stiffness by measuring time-to-peak tissue displacement directly along the acoustic radiation force axis. Embodiments achieve a highly accurate tissue stiffness estimate with minimal stiffness estimation error via use of an ultrasound device having less hardware complexity and which results in reduced sequencing complexity.