Measured inflation is set to remain below the bottom of the Reserve Bank of Australia's 2-3 per cent target range for longer after the official statistician re-weighted the benchmark consumer price index.

September quarter annual inflation of 1.8 per cent may have been 0.2 percentage points lower, according to the bureau's adjustment, and may dampen annual headline inflation by about 0.4 percentage points to 2 per cent over the next four quarters, according to Westpac.