A warning that Labour's plan to scrap school donations could leave some schools high and dry.

The party is promising to stop schools from asking parents for donations, and will front up with $150 per student per year instead.

But Pakuranga College principal Mike Williams said it doesn't take into account the differing reasons why schools ask for donations.

He told Larry Williams the effect will vary across different schools.

"It will make it a little bit easier for schools, and for some schools it will be a windfall, but it won't be enough to provide a full high-quality New Zealand free education."

LISTEN ABOVE AS PAKURANGA COLLEGE PRINCIPAL MIKE WILLIAMS SPEAKS TO LARRY WILLIAMS ON MIKE HOSKING BREAKFAST