Megalodon May Have Reached 65 Feet (IMAGE) Florida Museum of Natural History Caption Scientists have been trying to estimate the size of Otodus megalodon for more than a century, using the many fossil teeth the giant shark left behind. A new, more reliable way of calculating megalodon's length used tooth width instead of height, generating an estimated maximum length of about 65 feet. Credit Kristen Grace/Florida Museum of Natural History Usage Restrictions Please credit Kristen Grace/Florida Museum of Natural History. License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.