Measuring a bear skull requires two measurements: the greatest length and the greatest width. You add those two numbers together to get the final score. This scoring system, used by both the Boone and Crockett Club and the Pope and Young Club, applies to all North American bear species, and the process is straightforward once you know where to place your calipers.
The Two Measurements You Need
Bear skulls are scored using only the cranium (the upper skull, without the lower jaw attached). The two measurements are:
- Greatest length: The longest straight-line distance from the front of the skull to the back, measured along the midline. You’re looking for the maximum point-to-point distance, which runs roughly from the area between the brow ridges to the farthest point at the back of the skull.
- Greatest width: The widest distance across the zygomatic arches, which are the bony ridges that flare out on each side of the skull below the eye sockets. These arches are the widest point on almost every bear skull. Measure perpendicular to the centerline of the skull, wherever the maximum breadth falls.
Both measurements are taken in a straight line, not along curves. You measure to the nearest 1/16 of an inch, then add the two numbers. That total is the skull’s official score.
Tools for the Job
You need a set of outside calipers large enough to span the skull. The Boone and Crockett Club sells approved 18-inch spring outside calipers with an adjustable screw, which are wide enough to handle even the largest Alaska brown bear skulls. The adjustable screw lets one person take both measurements without needing a second set of hands to hold anything steady. The caliper tips should be fine and sharp for precise placement on the skull’s landmarks.
A steel ruler or tape measure alone won’t work well because you need to find the absolute maximum distance in each direction, and calipers let you “walk” the tips across the skull to locate the true widest and longest points. Once you’ve locked the calipers at the maximum span, you remove them from the skull and measure the distance between the tips with a steel ruler or folding carpenter’s rule graduated in sixteenths of an inch.
Step-by-Step Process
Remove the lower jaw completely. All scoring is done on the upper skull only. Clean the skull thoroughly so no dried tissue or cartilage inflates your measurements.
For greatest length, set the skull on a flat surface with the palate (roof of the mouth) facing down. Open your calipers and place one tip at the foremost point of the skull along the centerline, then place the other tip at the rearmost point of the skull, also along the centerline. Adjust slightly forward and backward on both ends to find the absolute longest span. The key is staying on the midline of the skull, not off to one side.
For greatest width, keep the skull in the same position. Place the caliper tips on the outside surfaces of the left and right zygomatic arches. Slide the tips forward and backward along the arches to locate the widest point. On most bears, this falls roughly at the midpoint of each arch, but it varies by individual skull. Measure perpendicular to the skull’s centerline.
Record both numbers to the nearest 1/16 of an inch. Add them together. That sum is your score.
The 60-Day Drying Period
A skull shrinks slightly as it dries, so record books require a mandatory 60-day air-drying period before an official measurement counts. The skull must dry at normal room temperature for at least 60 days after the animal was killed. Any measurement taken before that window closes is considered a “green score,” which is useful as an estimate but won’t be accepted as an official entry.
If you froze the skull before cleaning it, the 60-day clock doesn’t start until the skull is fully thawed and any boiling or degreasing is complete. The same applies to skulls that have been boiled for cleaning or freeze-dried: the drying period begins the day you remove the skull from the boiling pot or freeze-dryer and finish cleaning it. Store the skull in a dry, ventilated indoor space during this period. Don’t leave it in a garage that drops below freezing or in direct sunlight, as extreme conditions can cause cracking.
Green Score vs. Entry Score vs. Final Score
When you measure your skull at home before the 60 days are up, that’s a green score. It gives you a rough idea of where your bear stands relative to record-book minimums, but expect the final number to come in slightly lower after full drying.
Once the drying period is complete, a Boone and Crockett Official Measurer can score the skull. This produces an entry score. For trophies that meet the minimum threshold, a further verification step by a certified judges’ panel or club staff may be required before the score becomes final and the skull is entered into the permanent records.
Minimum Scores for Record Books
Both Boone and Crockett and Pope and Young use the same scoring system. The minimum entry scores (length plus width, in inches) for the Boone and Crockett Awards book and All-time book are:
- Black bear: 20 (Awards), 21 (All-time)
- Grizzly bear: 23 (Awards), 24 (All-time)
- Alaska brown bear: 26 (Awards), 28 (All-time)
- Polar bear: 27 (both books)
To put those numbers in perspective, a black bear skull scoring 21 inches would typically have a length around 13 inches and a width around 8 inches, though the exact split varies. An Alaska brown bear hitting the 28-inch All-time minimum might measure roughly 17 inches long and 11 inches wide.
Pope and Young minimums for archery-harvested bears are generally lower than the Boone and Crockett All-time thresholds, but the measurement technique is identical. Both organizations publish a shared Official Measurers Manual that governs how scoring is conducted.
Common Mistakes That Affect Your Score
Leaving tissue on the skull is the most frequent error. Dried cartilage on the nasal bones or connective tissue on the zygomatic arches can add fractions of an inch that will disappear when an official measurer cleans the skull properly, leading to a disappointing drop from your green score.
Measuring off the midline inflates the length reading. If you angle the calipers even slightly to one side, you may pick up an extra 1/16 or 1/8 of an inch that doesn’t reflect the true greatest length. Keep both caliper tips centered.
Using a tape measure draped over the skull surface instead of calipers gives you a curved distance, not a straight-line measurement. The score requires straight-line distances only.
Finally, measuring too soon is a common issue. Skulls can lose 1/16 to 1/4 inch or more during the full drying process, depending on the species and how the skull was cleaned. A green score that looks like it clears a minimum by a thin margin may fall short after 60 days. Be patient, let the skull dry completely, and then take your measurements.