It said it will be able to handle 700,000 online grocery orders a week - a combination of home delivery and click and collect - by the end of October, meaning it will have doubled capacity since the beginning of March.
Online grocery shopping has gone from around 7% of the UK market at the start of the pandemic to about 15% currently and pure online player Ocado reckons it could reach 30% over the next few years.
To meet demand Sainsbury's has added almost 200 new click and collect locations and nearly 1,000 more online delivery vans in comparison with last year. The group is also extending delivery times from 6:30 AM to 11:30 PM so it can serve more customers.
Britain's big four grocers - market leader Tesco, Sainsbury's, Walmart owned Asda and Morrisons - were quickly able to adapt their predominantly store-pick model to boost online capacity, enabling them to deliver growth and win share in the short term.
In contrast Ocado's capital-intensive and centralised fulfilment model meant it has not been able to dramatically increase its capacity during the crisis.
(Reporting by James Davey, Editing by Paul Sandle)