A method for dispensing a set number of items as a batch comprising the steps of: setting the set number of items in a batch; calibrating by forwarding items along a conveyor for a time interval; counting the number of items to fall off end of feeder in that time interval; calculating throughput per unit time; setting the conveyor to operate for a discrete time period calculated to approach but not exceed that required so that the running total reaches nut does not exceed the set number without otherwise adjusting conveyor settings; counting the number of items dispensed in the discrete time period; adding the number of items to fall off feeder in the discrete time period to running total, and repeating steps until the running total is greater or equal to the batch size wherein each iteration uses the number of particles per unit time in the preceding time period as basis for determining item through rate for calculating subsequent time period for operating the conveyor.