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Average Sizes:

The Very First Estimates of Megalodon Size:

The first ever attempt at a jaw reconstruction of megalodon took place in the early 1900's by Bashford Dean from the American Museum of Natural History. In 1909 he reconstructed a jaw that exceeded 10 feet. Based on this reconstruction, the resulting megalodon would have been over 80 feet in length. However, this reconstruction was based on unassociated sets of South Carolina teeth, as no associated teeth had yet been found. Today, we have associated teeth and know megalodon was much smaller.

The image to the left shows Dean sitting in his reconstructed jaw. This image and his article is in the The American Museum Journal: 1910, Volumes 9-10 page 232.

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The Recent Calculations of Megalodon Size:

There have been a number of proposed megalodon size calculations in the scientific literature. Below, I outline two methods and give charts for you to determine the size of your own megalodon based off your teeth.

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Shimada's Equations (Shimada, K. 2019):

This is the most recent method of calculating the maximum size of a megalodon.

Back in 2003, Shimada studied the dentition of Great White sharks of known body size, he concluded the roots and the crowns of the teeth did not grow at the same rate as the shark grew. Based on this finding, he came up with a linear relationship (Y = mX + b) between the crown height of a tooth and the size of the shark. He then used this equation to extrapolate the tooth size (CH) vs total body size (TL) of megalodon sharks. This linear equation had a different slope and intercept for each tooth position in the sharks jaw. These equations gave maximum sizes around 59 feet for megalodon sharks.

However, in 2019, Shimada re-examined the crown height and total length of Great White sharks as well as the rate of development of teeth as the shark ages. He again, used Great Whites, because they are the most similar living lamniform sharks to megalodon, as they have broad and serrated teeth.

This time around, he found there was too much variation among upper lateral teeth, and all lower teeth to draw definite conclusions. The only two teeth positions that gave reliable measurements were the first two upper anterior teeth (A1 and A2).

Shimada analyzed these tooth positions, made a linear analysis like before, and also made a new non-linear regression using the power function Y = aX^b. The non-linear regression takes into account the size-related shift in teeth associated with the age of the shark (due to dietary changes from juvenile to adult, and growth rate changes).

Shimada analyzed all of these regressions and concluded his older equations from 2003 overestimated the total length of the megalodon.

Shimada then combined the linear equation data from the A1 and A2 teeth to get a new maximum size estimate. His linear equation for the average of the A1 and A2 postion is as follows:

Y = mX + b -> TL = (11.788)(CH) + 2.143 where TL is the total length of the shark in cm, and CH is the Crown Height of the tooth in mm.

Don't worry if you are confused or don't want to do the math, below is instructions and a chart how to find your megalodon size:

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How to determine the size of a megalodon based on your tooth using Shimada's 2019 method:

Size chart for Megalodon body size using crown heights of either Upper A1 or A2 megalodon teeth.

When using this chart, remember this is only accurate to A1 or A2 teeth. All the other positions are too variable. Also rembember to use Crown Height, not Slant Height.
If the chart appears too small on your display device, click on it to see the full sized image.

Partial Associated Megalodon Dentition from Purdy et al., 2001. Here, I label A1 and A2 tooth positions for reference.

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The Older Method: Gottfried's Equations (Gottfried, et al., 1996):

This is an older method thats been handy for many years. Gottfried based his measurements on tooth heights of Great White shark teeth with known body lengths. Although it was an invaluable method many years ago, many paleontologists do not use this method anymore and instead use Shimada's method or other methods. Compared to other methods, Gottfried's equation appears to underestimate the current consensus on the length of a megalodon.

His equation from his paper (Gottfried et al., 1996) is as follows: TL(m) = a + b[UA2H(mm)]
His equation (converted into cm) with the constants added in is:

Length in meters = [(.96 x Upper A2 height in cm) - .22]

To use this equation, you need an upper A2 tooth. Also, when taking measurements, you need to measure the VERTICAL HEIGHT, not the Crown Height or the Slant Height.

To use this method, take a vertictal measurement of an upper anterior 2 tooth from the root lobe to the tip of the crown and then simply refer to the chart below. See the diagram showing how to measure it. The problem is, if you don't have an A2 tooth

One slight problem is if you don't have an upper A2 tooth, you need to "guestimate" the size of it based off your tooth and its position. You may want to refer to the dentition image in Shimada's section for this.

Chart showing Gottfrieds older method of using A II tooth height to determine corresponding megalodon lengths.

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Other Methods of Determining the Length of a Megalodon Shark

There are other methods developed by other paleontologists. Some appear to be more accurate than Shimada's method, however they are more complicated and often require more than an isolated tooth.

Jaw Perimeter:

One method by Dr. Mike Siversson measures the total width of the teeth in the upper jaw and compares it to living sharks. (Siversson, 2012). This method would be more accurate than basing measurements off of a single tooth because it uses more of the animal. Siversson estimates the maximum size megalodon to be around 19 m or 62 feet (Siversson, 2012).

Megalodon Vertebra Size:

One of the most accurate methods for the megalodon size does not use teeth. Instead it used vertebra and compares those vertebra to the lengths of similar sharks. Two researchers arrived at two different, yet similar, formulas for estimating the size of megalodons by this method.

The first is from the 1996 Gottfried et al. publication. In this paper, they compared the body length and vertebra size of the Great White shark and extrapolated it to megalodons. The equation is as follows:

TL = 0.22 + 0.058(CD)

Where TL is the total length of the shark in meters, and CD is the diameter of the largest vertebra centurm in mm.

The second vertebra method comes from Shimada (Shimada K, 2008). In 2008 he estimated the body length of Cretoxyrhina mantelli, a cretaceous shark. His equation (converted to meters) is as follows:

TL = 0.281 + .05746(CD)

Notice both equations are VERY similar. The only problem with this method is examples of vertebra from megaldodon sharks are rare. Also, you need the largest vertebra from the shark, which again is something very difficult to find.

A notable discovery of associated megalodon vertebra came from Denmark in 1983. A partial vertebra column of a megalodon was excavated from the Gram clay. There were 20 associated vertebra, with the largest having a diameter of approximately 23 cm (Bendix-Almgree et al., 1983).
Based on an average of both formulas above, this megalodon would have been around 13.5 m (44.3 feet) in length.

This a a 23 cm Megalodon Vertebra in Denmark - It's Figure 3 from: (Bendix-Almgree et al., 1983)

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I would like to thank Sam Cro for his expert help and input on this article. Thank you!

For much more information about megalodon sharks, go to the Megalodon Shark Gallery

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Recommended Megalodon Books and Items:

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Bendix-Almgreen, Svend Erik. (15 November 1983) Carcharodon megalodon from the Upper Miocene of Denmark, with comments on elasmobranch tooth enameloid: coronoi'n. Bulletin of the Geological Society of Denmark (Copenhagen: Geologisk Museum) 32: 1-32. (PDF).

Gottfried, Michael D., Compagno, Leonard J. V., and Bowman, S. Curtis. (1996) Chapter 7. Size and skeletal anatomy of the Giant Megatooth shark Carcharodon megalodon. pp. 55-66. IN: Klimley, A. Peter, and Ainley, David G. (editors). In: Great White Sharks the Biology of Carcharodon carcharias Academic Press. San Diego, CA. 517 pp.

Pimiento, Catalina and Balk, Meghan A.. (2015) Body-size trends of the extinct giant shark Carcharocles megalodon: a deep-time perspective on marine apex predators. Paleobiology, 41, pp 479-490. doi:10.1017/pab.2015.16.

Pimiento, Catalina, Ehret, Dana J., MacFadden, Bruce,J., Gordon Hubbell. (2010) Ancient Nursery Area for the Extinct Giant Shark Megalodon from the Miocene of Panama PLoS One. 2010; 5(5): e10552. Published online 2010 May 10. doi: 10.1371/journal.pone.0010552

Pimiento, Catalina, Gerardo Gonzalez-Barba, Dana J. Ehret, Austin J. W. Hendy, Bruce J. MacFadden, Carlos Jaramillo (2013). "Sharks and Rays (Chondrichthyes, Elasmobranchii) from the Late Miocene Gatun Formation of Panama". Journal of Paleontology 87 (5): 755-774. doi:10.1666/12-117.

Purdy, R., Schneider, V., Appelgate, S., McLellan, J., Meyer, R. & Slaughter, R. (2001). The Neogene Sharks, Rays, and Bony Fishes from Lee Creek Mine, Aurora, North Carolina. In: Geology and Paleontology of the Lee Creek Mine, North Carolina, III. C. E. Ray & D. J. Bohaska eds. Smithsonian Contributions to Paleobiology, No 90. Smithsonian Institution Press, Washington D.C. pp. 71-202.

Siversson, Mike. "Lamniform sharks: 110 million years of ocean supremacy" Royal Trell Museum Speaker Series. Western Australian Museum, Perth, Australia. March 28, 2012.

Shimada, K. (2008) Ontogenetic parameters and life history strategies of the Cretaceous lamniform shark, Cretoxyrhina mantelli, based on the vertebral growth increments. Journal of Vertebrate Paleontology 28: 21-33. doi: 10.1671/0272-4634(2008)28[21:opalhs]2.0.co;2

Shimada, K. (2003) The relationship between the tooth size and total body length in the white shark, Carcharodon carcharias (Lamniformes: Lamnidae). Journal of Fossil Research 35:28-33.

Shimada, K. (2019) The size of the megatooth shark, Otodus megalodon (Lamniformes: Otodontidae), revisited. Historical Biology, DOI: 10.1080/08912963.2019.1666840