Abstract: A method for determining properties of hydraulic fractures from measurements of pressure in a well made after stopping pumping fracturing fluid into the well (shut in) includes determining a first time after shut in whereinafter a decrease in measured pressure is caused by fluid leak off in a fracture. A second time after shut in is determined whereinafter the decrease in pressure is caused by fluid leak off, fracture growth and fluid pressure equilibration in the fracture. A third time after shut in is determined whereinafter the decrease in pressure is caused by fluid leak off, fracture growth, fluid pressure equilibration in the fracture and pressure drop in a near wellbore zone. Values of fluid efficiency, minimum stress and net pressure which are determined result in a calculated pressure with respect to time matching the pressure measurements within a predetermined threshold.