Picking correct level of resistance for a voltage divider
When you factor in the input impedance of the measurement device, your options will reduce but yes, there will be a range of values that can be chosen and you will tend to choose the option with the highest impedance that still produces acceptably low errors in measurement.

For instance, the ADC inbuilt in such devices as a PIC micro will not want to see a signal impedance more than a few kohm. As you go to greater values than a few kohm, the measurement error will increase and this can be alleviated, to some extent, by adding a capacitor from input to 0V.

So, read the data sheet for your measurement device, restrict your range of impedances and choose the highest set of resistors that give you an acceptable measurement error.

Sometimes you find that there is no overlap and, in cases like this you would use a spare IO line to activate a MOSFET to connect your battery to a potential divider. Then you can use quite low values and get good measurement accuracy and the battery energy spent is only for a short period of time in the bigger picture of things: -



Taken from this stack exchange answer (by me).