Isaiah Johnson was 22 1/2 inches long when he was born last week, WCJB-TV, Gainesville, reported Tuesday.
Nicia McNelley said she and her boyfriend were pretty surprised at how Isaiah came out.
"Me and his dad sat and thought, you know, maybe at the most 10 [pounds], maybe 12 [pounds]. But no... not 14," she said.
McNelley, who had Isaiah by Caesarean section Friday, said the baby has no health issues.
She said she hopes her son will turn out to be a football player.
Isaiah is the second-largest baby born in Florida this year.