The total cost came to nearly $500,000.
There are now eight staff as well as Mr Chouhan and his wife - three in the new kitchen at the back and five on the shop floor.
Some of the new workers were unemployed and are thrilled to have full-time jobs.
St John's is the last Four Square in Wanganui to be enlarged, in line with the policy of the group. Castlecliff, Aramoho and Eastbrook Food Market in Wanganui East have all expanded too.
"It's a small supermarket, carrying everything that a bigger one does," Mr Chouhan said.
He has owned the store for eight years and has been wanting to expand for the past three. It took time to get permission because the resource consent had to be publicly notified. Not that anyone was against the change.
"The community was 100 per cent behind it. No one objected, and we had supporting letters."
He is amazed at the loyalty of his customers, who kept coming in and buying even when construction was going on and the shop was dusty.
"I was surprised how much people love us and love the shop."