When regular unleaded is 205 cents a litre, who gets the money? Not, mostly, the servo. This guide breaks a litre of Australian petrol into its parts using the ACCC's late-August 2026 figures, explains how the price moves from the Singapore benchmark to the bowser, and sets out what happened to fuel excise during the 2026 supply crisis.
The five layers of a litre
Take the ACCC's five-city average of 205.5 cents for regular unleaded on 26 August 2026 and work backwards.
1. The international benchmark, about 104 cents. Australian petrol is priced off Singapore Mogas 95, the regional wholesale price for 95-octane petrol, converted into Australian cents at the day's exchange rate. In the week to 26 August that was around 104 cents a litre. It is the largest single component and the one nobody in Australia controls. Underneath it sits Brent crude at about US$94 a barrel, or 83 Australian cents a litre; the difference between the two is the refiner's margin, which was unusually fat in 2026.
2. Excise, 53.7 cents. A federal tax charged on refiners and importers, who pass it on. It is indexed to the consumer price index every February and August. The rate has been 53.7 cents since 3 August 2026.
3. Wholesale costs and margin, roughly 20 cents. Shipping from Singapore, insurance, terminal storage and handling, quality testing, additive blending and the wholesaler's margin. The ACCC uses the published terminal gate price (TGP) as a proxy for the wholesale price; on 26 August the five-city average TGP for petrol was 197.4 cents, which includes the benchmark, excise and GST on both.
4. Retail costs and margin, about 8 cents. The difference between the terminal gate price and the pump price: trucking the fuel to the site, the site's rent, wages, power, compliance, card fees and the retailer's profit. This is the layer that moves with price cycles and competition. In August 2026 a market analyst put retail margins at about 12 cents above their long-run average, a level that historically attracts discounting.
5. GST, about 18.7 cents. Ten per cent on the whole lot, including the excise, which is why every cent of excise costs 1.1 cents at the pump. GST is the 205.5-cent price divided by eleven.
Add excise and GST together and about 72 cents, or 35 per cent, of a 205-cent litre is tax. That is a higher share than the United States, where it is roughly 13 per cent, and a much lower share than the UK, where it is about 60 per cent.
The same sum for diesel
Diesel on 26 August averaged 250.2 cents across the five cities. Its benchmark is Singapore Gasoil 10 ppm, which was around 141 cents a litre that week, 37 cents above the petrol benchmark. Excise is the same 53.7 cents. Terminal gate averaged 244.1, so the retail layer was about 6 cents, thinner than petrol because diesel does not run price cycles. The entire 45-cent gap between diesel and petrol at the pump in August was in the international benchmark; six months earlier the two benchmarks were 11 cents apart.
How a change reaches the pump
International prices move daily. Wholesalers reprice their terminal gate prices to match. Retailers, though, generally only change their board price when they take a delivery, so the ACCC's rule of thumb is a lag of one to two weeks in the big cities and longer in remote areas, where tanks are refilled less often. During the excise restoration on 3 August, most capital-city sites had passed on the full 18.8 cents within a fortnight; a handful of remote towns took longer or passed on more, depending on when their last delivery arrived.
Note that the ACCC itself warned in 2026 that terminal gate prices were a less reliable proxy than usual, because during the March supply squeeze wholesalers stopped spot sales and prioritised contract customers, so few transactions actually happened at the published TGP.
The exchange rate
Because the benchmark is set in US dollars, the Australian dollar is the hidden fifth lever. A 5 per cent fall in the currency lifts the benchmark component by about 5 cents a litre with no change in crude. Through 2026 the dollar was relatively steady, so almost all the movement came from the benchmark itself.
What happened to excise in 2026
- Before 30 March 2026: excise was around 52.6 cents, with the next indexation due in August.
- 30 March: with five-city petrol near 257 cents and diesel near 322, the federal government cut excise by 32 cents a litre, initially to 30 June.
- 1 July to 2 August: relief continued at a reduced 16 cents.
- 3 August: full restoration, plus the deferred 1.1-cent CPI indexation, to 53.7 cents. Including GST, the maximum pump impact was 18.8 cents.
By 26 August the five-city petrol average had risen 10.2 cents from its 2 August level and diesel 13.2 cents, both less than the tax change, because the international benchmarks fell in the same period. The ACCC reported weekly on pass-through and found that in most locations the increase was at or below the expected 18.8 cents.
Why Australia is exposed
Australia refines less than a fifth of its own fuel, at Ampol's Lytton refinery in Brisbane and Viva Energy's Geelong refinery, both kept open with federal fuel security payments. Everything else arrives by ship from Singapore, South Korea, Malaysia, Japan, India and China. The country held about 30 days of diesel and 38 days of petrol in March 2026, well short of the 90 days the International Energy Agency recommends, which is why the government released strategic stocks, relaxed the sulfur standard to widen the pool of importable petrol, and cut excise all within a month of the Hormuz closure. None of that changes the price of a barrel; it changes how much of the world price the driver sees, and for how long.
What the servo actually makes
On a 205-cent litre, the retail layer of about 8 cents has to cover the site's operating costs before profit, which is why fuel retailers rely on the shop, the car wash and the coffee. Retail margin swings with the price cycle: at the top of a cycle a site can be making well above its average, at the bottom it can be selling below replacement cost, and the ACCC's quarterly reports track the average over the full cycle.
FAQs
How much of the petrol price is tax?
About 35 per cent at August 2026 prices: 53.7 cents of excise plus 10 per cent GST on everything, which together come to roughly 72 cents of a 205-cent litre.
Is there a state fuel tax?
No. State franchise fees on fuel were struck down by the High Court in 1997 and replaced with federal excise. Every state pays the same excise.
What is the terminal gate price?
The published price at which wholesalers sell fuel to buyers who turn up at the terminal. Few sales happen exactly at that price, but the ACCC uses it as a transparent proxy for wholesale movements.
Why is diesel dearer than petrol when it used to be cheaper?
The international diesel benchmark rose far more than petrol during the 2026 Middle East conflict, because the region supplies a disproportionate share of diesel and diesel-rich crudes. The gap at the pump reflects the gap in the benchmarks, not tax or retail margin.
When is the next excise change?
Excise is indexed to CPI each February and August. The next scheduled adjustment is in February 2027.