A win against Stoke tonight and a point at least against Southampton next week would suit him down to the ground.
Johnson said: "I think one more win guarantees we stay up.
"There are a few teams around the 37-point mark and none of them are too far away.
"It is so tight down there and most of the sides have difficult games coming up. One win definitely guarantees it for us; 100% if I'm honest.
"However, we want to try and get as many games as possible in terms of confidence and finishing the season on a high.
"I know we have to look behind us, but at the same time we should be looking to win the games ahead of us to finish as high up the league as possible."