Town have impressed in the first half of the season and are currently fifth after losing just once in their last 10 league outings.
"It depends how many points the top teams take off others, and it's difficult to gauge," he told the Swindon Advertiser. "But if you look at the averages over a period of years as to what gets you into the play-off places, then I would have thought 70 or 72 points would get you there.
"That could be wrong, I don't know, but you've got to be around that area to have a good chance. I would expect the top 10 teams to be challenging for the top six places, unless somebody comes along with a fantastic run. Or somebody could have a complete disaster and drop out.
"We think we can still get better and we will work to get better. But we've got to maintain the work that we have already done. You look at the league now and it means absolutely nothing. It's very important to be there in the last exchanges of the league programme."