Green politicians are leading a push to make Saturday bus rides free in the capital.

Greater Wellington Regional Councillor Paul Bruce is one of those behind the initiative, calling for a three month trial of zero fares for Wellington buses on Saturdays.

He says for him it's a no-brainer.

"Basically we've been reducing the congestion, we'd get rid of the parking issues and also it'll be really good for the retailers because at the present time it's actually really hard to get round on Saturday mornings."

Paul Bruce says there's huge unused capacity on Wellington buses with many over the weekend only ever half full.