The Australian dollar’s race to the bottom is not going to plan.

Reserve Bank boss Glenn Stevens wants a lower Aussie dollar to boost economic growth, but the European and Japanese central banks also want the same thing with their currencies.

In the past seven months the Australian dollar has dropped almost US20c, from US95c in July to US76c in early February, and most forecasters expect it to bottom out between US70c and US72c this year.

But in the same period, the Australian dollar has only fallen slightly against the yen, and is higher against the euro.

HSBC head of Asian currency research Paul Mackel said it’s becoming difficult for the RBA to engineer a faster depreciation for the Australian dollar.

“This is a very similar dilemma for other central banks too, how do you weaken your currency when others are trying to jawbone theirs lower,” he said.

“This is what many central banks want right now, they want their local currencies to do the heavy lifting.”

One of the main factors behind the Aussie dollar’s fall against the greenback is the US Federal Reserve’s intentions to raise its interest rate, while the RBA looks to keep its rate stable or cut it.

The local cash rate is at 2.25 per cent, while European, Japanese and the American interest rates are close to zero.

That gives the Australian dollar a yield advantage, which still makes Australia and its currency attractive to investors even though the RBA is looking to cut the cash rate further.

Because of this, there are some days when the Australian dollar doesn’t fall as far as it should, LTG GoldRock director Andrew Barnett said.

“When the market has been nervous it’s been difficult for the Aussie dollar to go lower because people have been wanting to buy that higher yielding currency,” he said.

“I think it can get to US70c on the back of two things – lower interest rates in Australia, which we’re going to get, and a lift in US interest rates in July or August.”

Mr Barnett said it won’t fall to US70c in the next month or two, but it will in the longer term. “If we see the Australian economy trend the way it has and the US economy trend in the opposite direction it’ll be US70c before Christmas,” he said.

Other drivers for the Aussie’s recent fall are big slides in the price of oil and iron ore, but that trend is not expected to continue.