Slant Height
Also: slant measurement, diagonal length
The standard way collectors and paleontologists measure a shark tooth: a straight line from the tip of the crown to the lowest point of the longest root lobe. It captures display size more fairly than width or vertical height.
Slant height is the measurement that matters most when you read a shark-tooth listing. It is the single straight-line distance from the very tip of the crown down to the bottom corner of the longest root lobe — the diagonal, not the vertical drop. A tooth has two such diagonals, one to each root lobe, and the longer of the two is taken as its official size. Because nearly every reputable dealer and most paleontologists report size this way, it is the number that lets you compare one specimen against another fairly.
Why slant height, not vertical height?
A tooth set on a table rarely sits perfectly upright, and crowns curve. Measuring the diagonal along the longest edge captures the tooth's true reach and display presence, while a strictly vertical measurement can shave a quarter-inch or more off the same specimen. When a stated size sounds generous, it is worth asking which method produced it.
Why it matters for value
For Megalodon teeth especially, value climbs steeply with size, so an honest, consistent measurement protects you. A genuine six-inch tooth is rare; a five-and-three-quarter-inch tooth measured generously is not the same thing. We report slant height to one standard across the collection, and our guide on grading and valuing shark teeth walks through how size interacts with completeness and color.
When you compare two teeth, make sure both sizes are slant heights measured the same way — otherwise you are comparing apples to oranges.