In a world of Afterpay, tap and go and online shopping, cash is - surprisingly - still king.

Many said they still carry notes and coins in their wallets, and the amount of cash in circulation has almost doubled in the past 10 years.

One person spoken to by RNZ said they carried cash they received in tips from working in a restaurant, while another said her mum often gave her cash.

But a third said it felt "flippant" to carry cash: "I don't really like to keep it because then I tend to spend it and I'm trying to control my spending."

Some said carrying notes and coins was essential in a natural disaster.

"I do love to have cash because I kind of feel secure," one man told First Up.