A week after the RBA surprised with its 50 basis-point interest rate cut, only two of 18 lenders surveyed passed the full reduction on to their customers.

Unicredit WA lowered its standard variable interest rates half a percentage point to 6.10 per cent, while New South Wales-based Police Credit Union dropped its Police Value Variable Home Loan to 6.24 per cent.

On average, though, most lenders have held on to 15 basis-points of the central bank's rate cut, according to Michelle Hutchinson of rate comparison site, RateCity.

“The current average rate drop we're seeing so far is 35 basis points, so we're expecting the average standard variable rate across our database to fall below mid-6 per cent when the rest of the home loan market announces rate changes and rates become effective by the end of the month,” said Ms Hutchinson.

Three of the four major banks have cut rates so far with ANZ Bank scheduled to update its 800,000 borrowers on Friday.

Westpac-owned Bank of Melbourne cut its standard variable rate by 41 basis points to 6.99 per cent to match NAB's rate, to be among the lowest. Among the most miserly is the Credit Union of Australia, which passed along only a 25 basis-point cut to 6.47 per cent.

RateCity cautioned consumers to use published rates only as a guide to costs.

“Borrowers need to remember that quite often it's not the standard variable rate that matters as most lenders offer better rates than these," said Ms Hutchinson.

Among those surveyed, NAB-owned UBank cut its standard variable rate loan to 5.83 per cent, down 40 basis points, after the RBA's move.

The new rates, though, may not have long to stick. Investors are currently betting there's a four-in-five chance that the central bank will lower rates a further 25 basis points on June 5 - kicking off another round of rate reviews by lenders.