Labour has vowed to cap public transport fares at $20 a week in main centres and $10 everywhere else if elected.

"This is real cost-of-living relief. It means cheaper commutes, more money left at the end of the week, and a public transport system that works for everyone."

The cap, which would be introduced on 1 July 2027, is $20 in Auckland, Wellington and Christchurch, and $10 everywhere else.

The party said it was higher in main centres because they offered more services, that cost more.

The policy would cost about $65 million each year, using about 1 percent of the National Land Transport Fund, Labour said.