Quotes for hail work group dents into sizes 1 to 4. In Australia the simple guide is coins: a 5 cent coin for size 1, 10 cent for size 2, 20 cent for size 3 and 50 cent for size 4. International standards are a little larger: roughly 18, 28, 36 and 48 mm across.
A dent estimator is just a sheet with holes of those diameters, so you can make your own from a white plastic sheet or laminated paper. Hold it over the dent and note which hole it fits.
Larger dents take longer to repair, which is why size is half of every price on a dent matrix.
Go deeper: this tip comes from the PDR eBook. See what is inside the eBook.
Prefer hands-on learning? See training dates. More PDR tips.