Tasmania lost 338 more people overseas than it gained from overseas in the year to March, according to Australian Bureau of Statistics figures.

Overseas migration was the biggest driver of Tasmanian population growth in recent years, exceeding the contributions made by net gains from the mainland and natural increase (births less deaths).

That has all changed.

Tasmania gained a net 1143 people from the mainland during the year.

That involved 13,444 people moving to Tasmania from the mainland and and 12,301 people leaving Tasmania for the mainland.

The two biggest states - New South Wales and Victoria - lost a net 17,796 and 18,191 residents respectively to other parts of Australia.

"Tasmania's population grew by 0.4 per cent over the year to the end of the March quarter, which, though down from 1.2 per cent over the year to March 2020, was, nonetheless, well above the national average," economist Saul Eslake said.

Mr Eslake said Australia's population growth rate slowed to just 0.14 per cent in the year to March 31.

He said that was the slowest since 1916.

"Net immigration over this period was minus 95,334, the first time it has been negative since 1946," he said.

"Victoria's population fell by 0.6 per cent, reflecting not only a loss of almost 54,000 people to abroad, but also another 18,000 people to other states as people fled what was, during this period, the lockdown capital of Australia."

The ABS estimated Tasmania's population on March 31 at a record 541,965.

It gained 1286 people during the year through natural increase, with the 5757 births exceeding 4471 deaths.