The B.C. NDP has promised relief for renters across the province in the form of an annual $400 renter's credit – a program that could cost more than $134 million in Metro Vancouver alone.

Leader John Horgan announced the credit at a news conference Wednesday in Vancouver, where vacancy rates are historically low and single-bedroom apartments can cost upward of $2,000 a month.

"What we're doing today is letting people that rent in British Columbia know that help is on the way. They're not forgotten," Horgan said.

The party said it intends to offer the program to every tenant across the province, including high-income renters, at least in the beginning.

Horgan couldn't confirm how many rental units there are in B.C., but the Canada Mortgage and Housing Corporation said there were 336,579 in the Vancouver census metropolitan area as of October 2016.

Paying each of the renters $400 a year would cost $134,631,600.

By comparison, the province's annual homeowner grant, which offers up to $770 for people who own homes worth up to $1.6 million, cost $809 million last year.

"If homeowners can have a homeowner grant, renters should be able to have a grant as well," Horgan said.

Both parties have made several costly promises in the lead up to May's election; CTV News has calculated the cost of every promise the BC Liberals have made since December at more than $5 billion.

The NDP didn't reveal how it intends to pay for the renter's credit, but promised the details would be shared when it releases its platform on Thursday.

"I think our plan is responsible, I think our plan is focused on people and we're going to be laying out our fully costed platform tomorrow," Horgan said.

Apart from the grant program, the NDP pledged to close loopholes in provincial legislation that allow landlords to implement massive rent increases well above the standard annual maximum of two per cent plus inflation.

One such loophole, which lets landlords apply for rent hikes based on market conditions in the neighbourhood, made headlines earlier this year when tenants in a building in Vancouver's West End were told their rent could be increasing by up to 43 per cent.

Asked about the NDP's plan Wednesday, Premier Christy Clark said it's not right that wealthy individuals living in pricey penthouses will be receiving the same $400 as everyone else.

The province’s homeowner grant has a cap that excludes people whose home is worth more than $1.6 million.

With files from CTV Vancouver's Scott Roberts