How to Estimate an Alligator's Length by Its Head Size

Locate the the midpoint between the eyes on the skull of an alligator. At night, use a flashlight to locate the eyes. They reflect a reddish-orange or bright pink when light is shone on them.

Estimate, in inches, the distance from the midpoint between the eyes to the midpoint between the nostrils. Record this number. If performing the measurement at night, use a flashlight to locate the nostrils.

Convert the number of inches to feet with 1 inch equaling 1 foot. For example, if the distance from the midpoint between the eyes to the midpoint between the nostrils is 4 inches, the estimated length of the animal is 4 feet.

To convert fractions of inches to feet, multiply the fraction by 12 inches. For example, if the distance from the midpoint between the eyes to the midpoint between the nostrils of the alligator is 5 ½ inches, convert the half inch to feet by multiplying 0.50 by 12 inches, resulting in 6 inches. The total length of the alligator is estimated to be 5 feet 6 inches. For one-quarter of an inch multiply 0.25 by 12 inches and for three-quarters of an inch multiply 0.75 by 12 inches.

Check your answer. Male gators typically grow up to 18 feet in length, while females seldom exceed 10 feet. If your result is more than 18 feet, recheck your calculations or remeasure the distance from eyes to nostrils.