Mortgage rates have reached their lowest point in 60 years, following the Reserve Bank's move to cut the OCR to 3%.

BNZ took 30 basis points off its two-year fixed rate over the weekend, dropping it to 4.69%.

And while it's never been cheaper to borrow, Dr Claire Matthews from Massey University's business school warns that it's not cause for celebration for all borrowers.

"Just because the interest rates have come down, and there's a lot of news about that, it may not affect your rate if you're on a fixed rate."

"Borrowers need to be cautious, because they need to remember that the reality is interest rates will go up, and they need to be able to afford that when it happens."

The drop mainly applies to fixed mortgage rates.

Dr Matthews said existing borrowers already locked into fixed rates will need to weigh up costs associated with getting out of that and onto the lowered rate.