Why Is Costco Fuel So Cheap in Australia, and How Much Do You Save?

Costco's bowsers are usually among the cheapest in town, but you need a paid membership to use them. This post checks how much cheaper Costco fuel really is in Australia, using our own daily prices for all 14 Costco fuel stations, the ACCC's city averages and WA's FuelWatch data. It explains why Costco can price so low, how it sits against the price cycle, and how many litres a year it takes to cover the membership fee.

Short answer: Costco fuel is cheap because Costco runs it on a thin margin to bring members to the warehouse, and earns its profit from membership fees instead. On 7 October 2026 our Costco prices were about 7–11c a litre below the ACCC's average for Sydney, Melbourne, Brisbane, Adelaide and Canberra, and about 21c below Perth's. At a 10c gap, the $65 Gold Star fee is covered after about 650 litres a year.

How cheap is Costco fuel right now?

On 15 October 2026, our 14 Australian Costco fuel stations averaged:

The base grade isn't the same everywhere. Costco sells E10 at its NSW and Queensland stations and Unleaded 91 in Victoria, South Australia, WA and the ACT (why, in our fuel grades guide). The Australia hub shows today's average and the cheapest Costco, and the Costco diesel page lists every station's diesel price.

Is Costco cheaper than the city average?

Yes, in every capital with a Costco. The ACCC has published weekly fuel price reports since the Middle East conflict pushed prices up in late February 2026. Its report of 9 October 2026, summarised on the government's fuel statistics dashboard and the ACCC weekly update page, gives average retail prices for 7 October 2026. We compared them with our Costco prices on the same day:

Sydney uses our Lidcombe, Casula and Marsden Park stations. Melbourne uses Moorabbin, Epping and Ardeer. Brisbane uses North Lakes and Bundamba. Canberra is Majura Park.

Three caveats. The dashboard rounds city averages to the nearest cent, so each gap could be half a cent either way. In NSW and Queensland we're comparing Costco's E10 with the city's regular unleaded, and E10 is normally a little cheaper, so those two gaps flatter Costco slightly. And 7 October was a Wednesday, the day Perth prices jump, which is why Perth's gap is so wide (see the price-cycle section below).

Across all 14 stations, Costco averaged 228.3c that day, against the ACCC's five-largest-cities average of 239c. That's a gap of roughly 11c a litre.

Is Costco cheaper than Ampol, BP, Shell and 7-Eleven?

Yes, at least in Perth, where we could check every brand. WA's FuelWatch publishes every station's price each day, so we averaged Perth metro prices by brand for Thursday 15 October 2026:

Costco was the cheapest brand in Perth that day. The nearest were small independents: Burk averaged 228.0c and Liberty 229.7c. Costco also led on the other grades. Its Premium 98 was 247.7c against a metro average of 266.8c, and its diesel was 251.7c against 277.2c for other branded premium diesels and 269.2c for regular diesel.

We couldn't do the same brand check for the eastern states. NSW FuelCheck, Victoria's Servo Saver and South Australia's scheme don't offer an open daily file we could download, and Queensland's open data had only reached August 2026. The city averages above are the best like-for-like comparison we have for those states.

Where does Costco sit in the price cycle?

Costco mostly stays out of the cycle. Most servos in the big cities have run a price cycle, with prices rising sharply, drifting down for days or weeks, then jumping again. The ACCC's price cycles page gives the average cycle length in 2025 as about 5 weeks in Sydney, 6 weeks in Melbourne, 6½ weeks in Brisbane, 2½ weeks in Adelaide and 1 week in Perth. The same page says regular cycles have mostly not occurred in Sydney, Melbourne, Brisbane or Adelaide since the conflict began in late February 2026. Perth's weekly cycle has carried on.

Perth is where you can see Costco's approach most clearly. We took FuelWatch's daily history and compared Costco with the Perth metro average for every day from 16 September to 14 October 2026:

Over those weeks, the market spiked every Wednesday and drifted down to a low each Tuesday. Costco's price didn't follow that pattern. Perth Airport changed its price eight times in 30 days, mostly in small steps that tracked the rise in wholesale prices, not the weekly swings.

So Costco sits near the trough all week. It doesn't always beat the trough, though. On Tuesday 13 October, Costco was at 228.7c after a rise two days earlier, and 86 of 444 Perth metro sites were cheaper. On Wednesday 14 October, only 17 were. If you fill up on a Tuesday at a cheap independent, you might match Costco. On any other day, Costco is very likely to win.

In the eastern cities our data shows the same habit. Lidcombe changed its E10 price seven times in 30 days, and Canberra only three times. With the cycles mostly paused this year, though, there's less of a trough to sit near. Check the price on the day, not the habit.

Why is Costco fuel so cheap?

Costco sells fuel to bring members in, not to make much money on each litre. Its fiscal 2026 annual report, filed on 7 October 2026 and covering its 15 Australian warehouses, says: "We believe our gasoline business enhances traffic in our warehouses; it generally has a lower gross margin percentage and lower SG&A expense relative to our non-gasoline businesses." Fuel made up 11% of Costco's worldwide net sales that year.

What that means in practice:

• Thin margins by design. Costco takes a small cut per litre because fuel buyers come back often and shop inside. Costco doesn't publish an Australian fuel margin, so we can't say whether it ever sells below cost. "Low margin" is accurate. "Loss leader" can't be proven from what it publishes.
• Membership fees carry the profit. Worldwide, Costco took in US$5.9 billion in membership fees in fiscal 2026, against operating income of US$11.7 billion. Fees alone equalled about half of operating income, so Costco doesn't need much from each litre.
• Big volume. Each station has many bowsers and draws members from a wide area, so fixed costs are spread across a lot of litres. Worldwide, Costco's fuel volume rose 7% in fiscal 2026.
• Simple sites. Costco stations sell a few grades, are self-serve, and take payment at the pump. There's no shop, no kiosk and no cash, so there are fewer staff and costs to cover.

None of this involves a cheaper fuel spec. Costco's fuel must meet the same national standards as any servo; see is Costco fuel good quality.

There's a hint of how thin the margin is in the wholesale price. On 15 October 2026 the posted terminal gate price for petrol, published by the Australian Institute of Petroleum, was 237.9c in Sydney, 237.4c in Melbourne, 234.3c in Perth and 235.4c in Adelaide. Every Costco in those four cities was below its city's price that day except Moorabbin, at 237.7c, 0.3c above Melbourne's. The terminal gate price is a posted spot price. Large buyers on supply contracts usually pay prices that aren't published, and Costco doesn't say what it pays, so this doesn't prove Costco is selling at a loss. It does show how little room it leaves above the wholesale market.

Tax isn't the difference. Excise is charged per litre at the same rate for every retailer, and the ATO lists 53.7c a litre for petrol and diesel from 3 August 2026, after this year's temporary excise cut ended. GST is one-eleventh of the pump price wherever you buy. Costco only competes on the part that's left.

How many litres does it take to pay back the membership?

You need a membership to use the bowsers, and the Gold Star fee is $65 a year on costco.com.au (see which memberships work at the bowser). Membership includes a free household card, so two drivers at the same address can share one fee.

Here's how many litres it takes to cover $65 at different savings per litre:

Worked example

Say you live in Sydney and fill a 50-litre tank once a week. That's 2,600 litres a year. At a 10c saving, you'd save $260 a year at Costco, or $195 after the $65 fee.

A lighter driver does 12,000 km a year in a car that uses 8 litres per 100 km. That's 960 litres a year. At 10c a litre the saving is $96, or $31 after the fee. That still pays off, but only just, and only if Costco is on your way. A 20 km round-trip detour in that car burns 1.6 litres. At today's prices that's about $3.70 a round trip, which cancels the saving on a 37-litre fill.

The sums change by city and by day. In Perth the gap averaged 15.7c over our window, about half as much again as the east-coast gap, and more than double it on Wednesdays. In Melbourne, on 15 October, Moorabbin was the dearest Costco in the country at 237.7c, so the gap there was smaller. Use the Costco fuel near me page to find the nearest station, then compare it with your usual servo on the same day.

Do Costco members get a discount on fuel?

Not on top of the pump price. The price on the bowser is the members' price. Gold Star, Business and Executive members all pay the same. There's no extra cents-per-litre discount for any membership level.

Executive membership adds a 2% annual reward on eligible purchases, but Costco Australia's member conditions say it is not calculated "on purchases of fuel", as in the US and Canada. Our Executive membership and fuel post has the details.

Do Costco employees get a discount on fuel?

We found no evidence that they do. Costco Australia doesn't publish a staff fuel discount, and we couldn't find one in any official Costco source. Employee reviews on Seek mention a free Costco membership as a staff benefit, which gives staff the same access to the bowsers as any member. As far as we can tell, they pay the same price per litre as everyone else. We couldn't verify the details of Costco Australia's staff membership benefit from an official source.

How to check today's price before you go

Prices move almost every day, and the gaps in this post will shift with them. Our state pages for NSW, Victoria, Queensland, South Australia, WA and the ACT show today's Costco prices. Each station page has unleaded, Premium 98 and diesel with a 30-day chart. Check the opening hours before you go, as the bowsers keep different hours from the warehouse.

For a fair comparison, look at the cheapest servo on your normal route on the same day, not the city average. In Perth, check FuelWatch for tomorrow's prices. Retailers there have to lock in their next-day price ahead of time, so you can see the Wednesday jump coming.