New Zealand's big four banks have all confirmed an increase in rates.

ANZ, BNZ and Westpac have followed the lead of ASB in bringing an end to the downward trend in interest rates.

ANZ has lifted its one-year rate by 31 basis points to 2.5 per cent, its two-year rate by 31 basis points to 2.9 per cent and its three-year rate by 25 basis points to 3.24 per cent.

BNZ increased its one-year rate by 36 basis points to 2.55 per cent, its two-year rate by 40 basis points to 2.95 per cent and its three-year rate by 26 basis points to 3.25 per cent.

Westpac's one-year rate went up by 36 basis points to 2.55 per cent, its two-year rate by 30 basis points to 2.89 per cent and its three-year rate by 30 basis points to 3.29 per cent.

ASB announced similar increases in its rates earlier this week, making it likely that the other major banks would soon follow suit.

The independents Kiwibank, TSB, the Co-operative Bank, SBS and Heartland have not yet lifted their mortgage rates. Neither have the smaller New Zealand providers HSBC and Bank of China.

This lift from the major providers comes in the same week as the release of inflation data, which has shown the cost of household essentials rising markedly by 3.3 per cent for the June quarter - the biggest increase in 10 years.

An increase in interest rates will place further pressure on homeowners, many of whom are currently burdened by large mortgages.

To put this into context, a 0.36 point shift in the two-year rate would equate to an additional $1824 per year ($152 per month) for a recent home buyer paying off an $800,000 mortgage across 30 years.

The Reserve Bank this week kept the Official Cash Rate at a record low 0.25 per cent, but economists from ASB and ANZ have forecast a rise as early as August.

While an increase in rates will hit homeowners, the flip side is that those with savings in the bank will benefit from a boost in interest earnings.

Kiwibank released a statement confirming it would be increasing its term deposit rate to 1.2 per cent from 0.8 per cent for its 200-day term.

ASB has increased its six-month term deposit interest rate by 0.2 per cent, with the rate rising from 0.8 per cent to 1 per cent. The biggest increase was for the three-year term deposit, which saw an increase of 0.3 per cent from 1.4 per cent to 1.7 per cent.

Westpac has increased its three- to five-year fixed term deposit rates by 20 basis points each. A five-year fixed-term deposit now offers 2 per cent per annum upon maturity.