The horrific rate at which New Zealand soldiers died in the ill-fated Gallipoli campaign of 1915 may be far less than previously thought, new research shows.

Officially, 2721 New Zealand soldiers are said to have died as a result of Gallipoli service, from 8556 who served on the peninsula - a rate of 31.8 per cent.

But new research by Hamilton author Richard Stowers suggests that 19.8 per cent of New Zealanders who served on the Anzac escarpment lost their lives.

He said 2779 died (58 more than previously thought) but there were 13,977 New Zealand troops altogether (5421 more than earlier estimates).

Stowers said theoretically 18,000 New Zealanders could have served in Gallipoli and his figures were "quite conservative".

Stowers' figures have been drawn from official casualty lists and reinforcement details. They do not include soldiers evacuated from the war zone as sick.

If wounded soldiers (5212) are included, Stowers said the casualty rate is 57.2 per cent, against the official tally of 92.7 per cent.

Some soldiers were wounded more than once, and many returned after earlier being wounded and evacuated.

"I think the only way to know how many New Zealanders served on the peninsula would be to go through every [military personnel] file and see if it says they were there or not," Stowers said.

His new book, Bloody Gallipoli, gives a day-by-day account of the campaign and lists those who died between April 25 and December 20, 1915.

It includes the 58 "new" names of soldiers who died at Gallipoli, but research by the New Zealand Press Association shows there are more yet to be counted.

For example, Private Horace Braithwaite, of Otago Battalion, was grievously wounded on the peninsula in early May 1915. He was returned to New Zealand and died of his wounds in Dunedin on January 15, 1916.

Private Braithwaite, whose brother Private Jack Braithwaite was executed for mutiny in 1916 and pardoned in 2000, is not included in Stowers' figures.

English military historian and Gallipoli expert Christopher Pugsley said he was not surprised by Stowers' findings.

"Richard is a master at ferreting out individual detail," Dr Pugsley said.

It was not the first time anomalies had been found. "The reality is the whole nature of putting figures together is based on certain judgment calls anyway," Dr Pugsley said.

Military historian Glyn Harper said the time was right for further study on New Zealand's World War I experience, particularly a detailed statistical study of men and women who served.

"It's really time there was an official history on New Zealanders in the Great War.

"We don't have one, and we really need to know more about these people and what they went through, and what their legacy was for the nation."

NZ death toll

Official casualty rate: 31.8 per cent (2721 men out of 8556).

New estimate: 19.8 per cent (2779 out of 13,977).