Methods and apparatuses for automatically measuring memory cell threshold voltages are disclosed. Measurement circuitry includes an internal reference current generator, a plurality of memory cells and a bit line pre-charge reference circuit. If the reference current is greater than the memory cell current, the bit line voltage will increase. Conversely, if the reference current is less than the memory cell current, the bit line voltage will decrease. The reference current is generated in large steps until a comparator, that compares the bit line voltage and a bit line pre-charge reference voltage, is switched. The reference current then generates a current in small steps until the comparator is again switched. The reference current converges on the memory cell current within an accuracy of 10 nA. The memory cell threshold voltage is then determined from the memory cell current. Systems including memory according to an embodiment of the invention are also disclosed.