Justin King, chief executive, said the retailer was on track to build an extra 2.5m sq ft by 2011, equivalent to a 15% growth in store space.
Last year the country’s third biggest supermarket chain spent £900m on new stores, including building 38 major supermarkets.
A further £1.1 billion of capital expenditure is earmarked for 2010/11.
This includes plans to open up to 100 more smaller convenience stores.
King said: “Today, only around 20% of the UK population live within a 15-minute drive of one of our stores.
“Consequently, we are stepping up plans for extensions and completed 13 larger, more cost-effective extensions in the year.”
He said Sainbury had built up a strong pipeline which would see 15 to 20 supermarket stores built each year. The retailer presently holds planning consent for 70 stores.
King said: “This will result in the proportion of the population within a 15-minute drive time doubling to around 40 per cent by 2014.”
The retailer said it expected to achieve a pre-tax rate of return of more than 15% on the current investment programme.