There are 6 standard measurements used to quantify shark teeth.

The 3 common ones are "Slant Height", "Width" and "Weight".  ("Slant Height" is a shortened form of "Major Slant Height".)

The 3 uncommon ones are "Minor Slant Height", "Vertical Height" and "Thickness".

The "Slant Height" measurements are taken from the blade tip to the tip of the root ears on a diagonal.  The longest becomes the "Major Slant Height" and the shorter one becomes the "Minor Slant Height".  The "Width" measurement is taken perpendicular to the midline of the tooth along the widest part of the root.  "Vertical Height" is taken along the midline of the tooth from the blade tip to a line drawn between the tip of the root ears.  "Thickness" is measured as the tooth is lying Flat Side down on a flat surface to the highest part of the Display Side root.    It is important to note that these measurements are taken ON AN IMAGINARY STRAIGHT LINE that runs through the body of the tooth and not along the curved surface.    See drawing above.

Have you ever seen teeth advertised as "about 5 inches" or "right at 6 inches or "nearly 4 1/2 inches"?  Most other dealer and auction seller measurements are inaccurate.  Many of these measurements are downright incorrect.  Measuring fossils with a ruler is next to impossible because of Parallax Error.  We take all our measurements with a CALIBRATED DIGITAL MICROMETER to eliminate this error.  The MICROMETER we use has a resolution of 0.01mm or 0.0005" (5 ten thousands of an inch).  We measure in millimeters and then convert to decimal inches which is far more accurate.  (25.4mm = 1 inch).  Similarly, we measure weight in grams and convert to ounces.  (28.35 grams equal 1 ounce.)    See photos below.