The National Australia Bank has split from its three major rivals, cutting its standard variable mortgage rate by only 20 basis points.

The three other major banks have passed on the full 25-basis point cut announced by the Reserve Bank of Australia yesterday.

But NAB says its standard variable rate will be the lowest of the four major lenders, at 7.47 per cent from November 7.

NAB announced its move this morning, just after ANZ said it would give its customers the full rate cut.

Westpac and Commonwealth Bank both announced they would hand the full rate cut to their borrowers just hours after the central bank's decision yesterday.

Westpac's standard variable rate will be 7.61 per cent from November 14, Commonwealth Bank's will be 7.56 per cent from November 4 and ANZ's rate will be 7.55 per cent from November 14.

NAB's decision comes after it ran an advertising campaign earlier this year in which it said it had "broken up" with the other banks.

NAB personal banking group executive Lisa Gray says the bank has had the lowest rate of the major banks for more than 28 months.

"Our commitment is to be competitive and for more than two years NAB has offered the lowest standard variable home loan rate of any of the major banks," Ms Gray said.

"NAB has led the industry and abolished the most disliked fees including overdrawn fees, account-keeping fees and mortgage early-exit fees for new and existing customers."

St George and Bank of Queensland also have cut their standard variable home loan rates by 0.25 per cent.