There are two different criteria you should be looking at when determining which set of calipers to purchase. One is resolution and the other is accuracy. It can be confusing, but there is a difference. Resolution refers to the range of measurement while accuracy refers to, you guessed it, how accurate the calipers are. For instance, a set of calipers may have a resolution of 0.0005 - 6 inches, but it may only be accurate down to 0.001 inches. That doesn’t mean you can’t use them to measure smaller increments, it just means you can’t rely on as much accuracy at smaller intervals.