For Australian central bank watchers, it seems no one is neutral on where neutral actually is.

Economists and money markets are betting the point at which interest rates are neither stimulative or restraining is lower than the central bank's estimate of about 3.5 per cent.

And if markets and analysts are right, that means there's less stimulus in the economy than the Reserve Bank of Australia thinks, even before factoring in the tightening effect of a rampaging currency.

While the board will likely leave its official cash rate unchanged at a record-low 1.5 per cent on Tuesday, the release of the neutral estimate almost two weeks ago sent the Aussie dollar soaring in the belief policy makers were laying the ground to tighten.