Jagielka celebrated a 35th birthday back in August and the former England defender has been a rock in Everton's back four since 2007.
Centre-backs begin to lose a lot of their pace as they age for obvious reasons, but Calvert-Lewin, a £1.5 million addition from Sheffield United back in January, says that the former Blade is still "rapid" in spite of his advancing years.
Asked who Everton's speed demon was, the 21-year-old told Sky Sport's Soccer AM: "I like to think I'm up there [but] Jags is quick, honestly.
"You'd be surprised - he's rapid. I think I'd win [in a race] but he's surprisingly quick."
Jagielka came close to leaving the Toffees after a 10-year stint at Goodison Park this summer but manager Ronald Koeman elected to keep him.
The veteran defender has started four Premier League games this season and could be set for further opportunities by virtue of how poor Ashley Williams has been.
Williams, 32, continued to attract the spotlight for negative reasons on Monday after losing possession in the build-up to the goal in the Republic of Ireland's 1-0 win over Wales last night, though his goalkeeper Wayne Hennessey put him an awkward spot.
Nevertheless, it's been a very testing season for the former Swansea City captain and time will tell how he responds.