That will include new-boy Liam Vincent, who is deemed to be one for the future, and Reeco Hackett-Fairchild, who spent a largely uneventful loan spell at Southend last season.
But with Ronan Curtis also attracting interest and Pompey open to offers for players, that figure could easily drop as Danny Cowley overhauls the playing squad he inherited from Kenny Jackett.
With that in mind, we look at those 13 players who are currently contracted to the Blues and assess what their futures might hold.
9. John Marquis - Centre-forward
Pompey's top-earner, following his £1m moved from Doncaster Rovers in 2019. The striker finished last season as the Blues' top scorer with 18 goals but Danny Cowley's unsuccessful pursuit of Jayden Stockley shows he's in the market for a centre-forward. Whether that's to play alongside Marquis or to replace him remains to be seen. That could depend on whether any suitable offer comes in for the 29-year-old. Photo: JPIMedia
10. Haji Mnoga - right-back
Haji Mnoga finds himself in the the rare position of being the only out-of-contract player that Pompey have kept this summer. Is highly thought off at Fratton Park but needs more experience. That could see him head out on loan when the opportunity arrives and Cowley has more bodies in the building. Photo: JPIMedia
11. Sean Raggett - Centre-back
When Danny Cowley arrived back in March, Sean Raggett was his only connection to the then Pompey squad, having managed the defender at Lincoln. It seemed a match made in heaven, with Raggett a player Cowley previously plucked from relative obscurity. Yet the head coach's decision to pick Paul Downing ahead of the defender for the final day of the season casts doubts on that theory. Photo: JPIMedia
12. Liam Vincent - Left-back
The 18-year-old represents Danny Cowley's only signing to date. Signed from non-league Bromley, he's one for the future. Expect him to be involved in some capacity next season - but will be down the pecking order. Photo: JPIMedia