New Plymouth District mayor Neil Holdom says the council's use of consultants is tracking down.

New Plymouth's mayor has defended the district council after it paid outside consultants more than $4 million in the last 18 months.

Neil Holdom said the $4.2 million spent since his election in October 2016 was "tracking down" on what the previous council had spent and consultants were only being used where the council did not have its own expertise.

"You're always going to need to bring in external consultants for things we don't do day to day, business as usual," he told Radio New Zealand.

"I mean if we want to design a bridge, when was the last time New Plymouth District Council put a bridge in? So, yep, you bring someone in."

During his election campaign Holdom had queried the use of outside consultants, questioning the $4.7 million spent in the March 2016 financial year.

"At a high level the costs being expended on consultants have come down significantly and that reflects my commitment to the ratepayers prior to the election," he said.

Figures released under the Local Government Official Information and Meetings Act break the $4.2 million spent since October 2016 as: