As fuel excise set to be halved, when will fuel prices in Australia go down?

Australians could wait days or even weeks for much-needed relief at the petrol pump after Anthony Albanese announced the reduction of a key fuel tax for three months.

The fuel excise, a tax on petrol, will be halved, seeing petrol prices finally go down after soaring for weeks due to the supply issues arising from the Middle East conflict.

These changes and others will take effect today, with Australians now having more certainty as to when they will pay less at the bowser.

LIVE UPDATES: Trump threatens to wipe out critical Iranian island if deal isn't reached 'shortly'

When will petrol prices go down?

The fuel excise cut will go into effect today, April 1.

Given it will be signed into law, it means it will have an instant impact on the cost of fuel, with Albanese claiming it would reduce the cost of petrol by 26.3 cents per litre.

But - stations will have to first sell the batch of fuel they had paid for at the full rate of fuel excise.

The changes may not be immediate, unless you are filling up at a station that has a high turnover of fuel, and a new batch taxed at the half rate has already been bought and filled.

It could take a few days – or even weeks in some regional or rural areas – for the price decreases to flow on to the pump.

"It depends really on the turnover of the station," Minister for Health Mark Butler told Today.

"It will be a few days at those very high turnover stations in the cities but as much as one or two weeks in other communities."

Treasurer Jim Chalmers earlier said filling up a 65l tank with petrol would be $19 cheaper once the changes happen.

According to the latest figures released by the Australian Institute of Petroleum, unleaded petrol costs around $2.53 a litre, with diesel well over $3 a litre, which is why farmers and heavy transport industries are being hit particularly hard.

A further measure of relief is the temporary halt of the heavy road vehicle user charge, which hits truckies with a 32.6 cents per litre charge on diesel.

This will also be in place for three months.

READ MORE: Why thousands of Aussies plan to cancel their health insurance tomorrow

Why is petrol so expensive right now?

Longer term, the price of oil will continue to keep petrol prices high, and that is something out of the governments control.

Crude oil currently costs around $115 a barrel; it was sitting in and around the $65 region before the Middle East conflict broke out and impacted the Strait of Hormuz, a vital shipping lane in the region for worldwide oil trade.

Not only is oil more expensive, the volatile situation in the Middle East means it is harder for oil to get to Australia, even though the government insists supply isn't a longer-term issue at the moment.

With increased demand, more people are rushing to fill up - some even hoarding petrol - which is leading to shortages and more pain at the pump for Australians in the cities and in the rural areas.

READ MORE: Why NSW government has decided not to offer free public transport for commuters amid fuel crisis

Are petrol stations running out of fuel?

Hundreds of petrol stations across Australia have reported running out of petrol or diesel at different points in the last two weeks.

It is difficult to ascertain the true levels, though states and territories often release daily figures of how many petrol stations are out of fuel.

Some petrol stations run out of both petrol and diesel, though some only run out of one or the other.

For example in New South Wales last weekend, 66 petrol stations were out of fuel.

However, Transport Minister John Graham said some regional areas that were low on fuel previously had been resupplied.

READ MORE: The timeline of events from Porepunkah shooting to cop-killer's death

How long will these petrol prices last?

As mentioned before, the only way we will see prolonged relief at the pump will be when the price of oil drops.

That almost exclusively hinges on the fate of the Middle East conflict, which shows no signs of slowing anytime soon.

NSW Premier Chris Minns cautioned his state to prepare for long-term disruption as a result of the war.

"I am not seeing any indication that this will be resolved in 30 days," Minns said.

"I don't know whether it is going to be over in a week, or whether it's going to be a prolonged situation... but we have got to prepare for every eventuality."

How many days of petrol does Australia have left?

Energy Minister Chris Bowen insisted Australia still has a month of supply of petrol, and said shipments are still coming in despite some cancellations.

Briefing parliament yesterday, he said the country has nine days' worth of petrol, 30 days' worth of diesel; and 30 days' worth of jet fuel.

Bowen said any shipments that were cancelled have been more than properly replaced, as he looks to ease fears of a drop in supply.

NEVER MISS A STORY: Get your breaking news and exclusive stories first by following us across all platforms.

• Download the 9NEWS App here via Apple and Google Play
• Make 9News your preferred source on Google by ticking this box here
• Sign up to our breaking newsletter here