New Zealand would have a new flag if it were up to six of its 71 electorates.

A majority of voters in Bay of Plenty (51.4 per cent), Clutha-Southland (50.4 per cent), East Coast Bays (51.1 per cent), Ilam (50.8 per cent), Selwyn (51.7 per cent) and Tamaki (51.9 per cent) opted for a new flag, according to preliminary results.

All of those areas are held by National MPs.

In Prime Minister John Key's Helensville electorate, 56.6 per cent of people chose to keep the current flag.