Abstract: A method for measuring and adjusting the toner density of black toner in a multi-color copy machine includes first developing and transferring a layer of yellow toner (132) onto the surface of a transfer belt (18). A crosshatch pattern (134) of black toner is then developed and transferred onto the surface of the yellow toner layer (132) in a series of patches (138)-(148). The cross-hatch pattern (134) is comprised of vertical and horizontal bars (136) that are spaced a predetermined distance apart and have a predetermined width. A toner density sensor (40) is disposed over the surface of the transfer belt (18) to measure the toner density. The amount of toner deposited on a photoreceptor belt (12) is altered by varying the grid voltage on a charging corona (28) during the developing step to provide multiple toner densities for each of multiple patches (138)-(148). This data is then extrapolated to determine what the grid voltage on the charging corona (28) should be for the desired toner density.