The Blues boss is refusing to give up hope of breaking into the top two during the final 10 games of the League One season.
Yet the play-offs are looking increasingly likely following Saturday’s 2-1 defeat at Charlton.
The Addicks themselves finished in last season's final play-off position in sixth, with 71 points.
Jackett believes that tally will again earn qualification this term, with Pompey presently on 65 points.
And with 30 points still to play for, Pompey can be expected to reach the required total comfortably.
The Blues boss said: ‘You look at the tradition of it and anything from 71-76 points is where the last play-off position is.
‘Charlton were sixth last year and got 71 points – and it looks like that figure is again going to be the case this year.
‘Traditionally that it what you look at, while the top two for this division are high, every season they are high, it was 98 and 96 last season, that’s very good.
‘We have to keep chasing the top two and a number of clubs will believe out of those final 30 points up for grabs you can find the right equation which can get you a high number – and you have to go for that.
‘We have to do everything we can to go for it, we are definitely capable. Capable players, capable squad, capable club, we are capable of it and if that is the case we want to do well.
‘We want to be in a situation where we are doing everything we can to go up – and for that you need good form and good performances.
‘Luton and Barnsley are in the box seat and we are chasing. We need eight or nine wins out of the last 10 to get there.’
Charlton inflicted the double over Pompey, in the process leaving Jackett’s men eight points adrift of the automatic promotion spots.
In addition, the Blues are now 11 points short of leaders Luton.
They do, however, remain in fourth place – 10 points ahead of Doncaster who occupy the final play-off slot.
Jackett added: ‘Saturday was a different game to Bradford, it was a tough match and the quality of the opposition does come into it.
‘I wasn’t necessarily disappointed, I thought there were key moments and then, with the big chances at the other end, we want to be finishing those.
‘We did finish strongly. Charlton are then going to work backwards slightly and try to hold onto their lead, which is something they did successfully.
‘If you lose games, you want to lose games on top, putting pressure on the opposition, everything you can to try to get into it, which we did.’