Among those numbers are influential first-team regulars Marcus Harness, Louis Thompson and Michael Jacobs as well as Player of the Season Sean Raggett.
Danny Cowley revealed the Blues are yet to finalise talks with any of his out-of-contract contingent over new deals – opening up the possibility of them leaving for free come June.
But how does the Fratton Park outfit’s numbers of potential free agents compare to those across the rest of League One?
We’ve taken a look at the sides with the most players out-of-contract in the summer and who could have the biggest rebuilding job ahead.
Here’s what we found.
5. MK Dons - 5
Out-of-contract players: Daniel Harvie, Sullay Kaikai, Dean Lewington, Zak Jules, Tennai Watson. Photo: Pete Norton
6. Barnsley - 5
Out-of-contract players: Luke Thomas, Clarke Oduor, James Norwood, Jordan Helliwell, Aidan Marsh. Photo: Morgan Harlow
7. Morecambe - 5
Out-of-contract players: Ryan Cooney, Courtney Duffus, Ashley Hunter, Ryan Delaney, Andre Mendes. Photo: Pete Norton
8. Plymouth - 6
Out-of-contract players: Ryan Hardie, Connor Grant, Danny Mayro, Brendan Galloway, Niall Ennis, James Bolton. Photo: Michael Steele