The numbers, taken from NBN Co's own website, indicate about 1½ premises across the state were passed by fibre each day over the period.

But NBN Co spokesman Trent Williams said the data was not representative of actual rollout rates.

Mr Williams said since April, premises were no longer counted as passed by fibre until 90 per cent of the surrounding area was declared ready for service.

"This has been perceived incorrectly by some as a slowdown," Mr Williams said.

"It is merely a change in reporting that more accurately reflects the customer's experience."

He said construction was in fact continuing to ramp up.

Mr Williams said as of August 14, 22,000 Tasmanians were connected to the network and another 57,000 were able to order a service.

He warned against looking at NBN Co's week-to-week figures to try measuring its construction program.

In turn, Tasmania's peak industry body called on NBN Co to fix how it measures its figures.

"If NBN Co doesn't believe the statistics are valuable they should consider producing a set of statistics that are," TasICT chief executive Dean Winter said.

"For example, statistics about the wait time for NBN connections would be extremely enlightening," he said.

The latest figures also showed Tasmania lagged well behind some mainland states for rollout rates.

Mr Winter said Tasmania was promised "first mover advantage" through the NBN construction program, but had now slipped to the back of the pack.

"We're watching Mr Turnbull and his various MPs push the big, shiny NBN button in Brisbane and Sydney but seeing very little progress here," he said.

Mr Winter said business certainty was suffering as a result, with ICT companies unsure about technologies to be used in the rollout and the scheme's future beyond 2015.