Movable computer ruler (MCR): A new method for measuring the size of Toxoplasma gondii cysts, tachyzoites and other selected parasites

► A new method for measuring the size of parasites and other objects using optical microscopy. ► A designed movable computer ruler (MCR) derived from digital images of a stage micrometer. ► MCR can be superimposed on images of parasites to measure their size. ► Width, height, pixel number and density are fixed for every image. ► MCR method makes it easily and fast applicable.