When we price stumps we typically will come out to see them 1st hand or we will request multiple pictures that clearly demonstrate scale and surroundings. Every grinding situation is different and grinding often can be challenging work so we don't price this service hourly like our others. When sizing a stump please keep in mind we must grind a minimum of 3-4 inches below surface grade to create a new area for grass root regrowth. This means that all the roots need to be chased and eliminated The grind area expands the deeper we go.
Beyond size, access, obstacles tree type cleanup and ground conditions factor in as well. Very little is standard.