Abstract: A hand-held, battery powered, portable monitor for recording elapsed time and for calculating cost charges based upon this elapsed time. The monitor selectively displays constantly updated elapsed time and constantly updated charges which accrue with elapsed time. A clock generates a data signal relating to elapsed time, and a memory device is provided with data relating to charges accruing with respect to the elapsed time. A calculator employs stored data to calculate constantly updated accrued charges, and to generate a corresponding data signal. The data signals regarding current elapsed time and current charges are received by a display, and these values are displayed. The device includes a keypad for entering data and operating commands, a battery power source, and an on-off switch. The memory can store cumulative elapsed time and cost data.