Deputy Prime Minister, Bill English, is encouraging Kiwis to have their say on what New Zealand's flag should look like.

The first postal referendum, which will give New Zealanders the first ever opportunity to vote on the flag that best represents them, begins today and runs until 11 December.

Mr English says voters should take advantage of the opportunity to rank the five alternative designs selected by the Flag Consideration Panel.

"This is a once in a lifetime opportunity. 

"Very few governments around the world have ever asked their citizens for their views on the design of their national flags.

"I'd encourage everyone who is eligible to vote to have their say and choose the flag they feel best represents New Zealand's proud, pioneering past and its exciting, ambitious future," he says.

The Electoral Commission aims to announce the official result of this first referendum on 15 December.

That design will then proceed to a second binding referendum in March, where voters will choose between it and the current flag.