What a giant roll of foil taught me about smarter grocery shopping

Twelve months ago, I bought a 150-metre roll of aluminium foil and a 120-metre roll of baking paper from Costco. I am still using both. Not even close to finished. That, right there, is bulk buying at its absolute best – products you use constantly, that don’t expire, that cost a fraction of what you’d pay buying the standard supermarket size over and over again.

But here’s the thing about bulk buying: it is not always the bargain it appears to be. And with household grocery bills continuing to climb, it is worth knowing exactly when going big saves you money – and when it quietly costs you more.

Consumer group Choice recently analysed prices across 80 packaged products, comparing bulk retailers including Costco, Amazon and Woolworths Everyday Market against standard supermarket prices at Coles and Woolworths. The results were illuminating – and not always in the direction you’d expect.

When bulk buying genuinely wins

Choice found that buying in bulk was cheaper 59 per cent of the time, with discounts ranging from 5 per cent all the way to 60 per cent. The categories where bulk buying delivered the biggest savings were cleaning products and personal care items – things like body wash, baby wipes and surface sprays.

Some of the standout examples: a 5-litre pack of Windex Glass on Amazon was 60 per cent cheaper than buying the standard 500ml bottle from Coles. Dove Body Wash in a 2-litre pack was 50 per cent cheaper than its supermarket equivalent. Huggies Newborn nappies came in at just 25 cents each on Amazon, compared to 36 cents at Woolworths.

For Starts at 60 readers, the products that tend to offer the best value when bought in bulk share a few common characteristics: they have a long shelf life, you use them regularly, and they don’t require refrigeration. Think along the lines of:

Aluminium foil and baking paper (as proven above)

Dishwasher tablets and laundry detergent

Toilet paper and paper towels

Canned goods – tomatoes, tuna, legumes

Olive oil and cooking oils

Coffee and tea

Personal care staples – shampoo, body wash, soap

Vitamins and supplements you take daily

Bin liners and zip-lock bags

Cleaning products – surface sprays, floor cleaner, dishwashing liquid

These are the categories where the maths reliably works in your favour, and where a Costco membership or an Amazon bulk order can deliver genuine, ongoing savings.

When bulk buying turns against you

Here is where it gets interesting. Choice found that some bulk products were significantly more expensive than their standard supermarket counterparts – and the examples are genuinely surprising.

A 2-kilogram bulk pack of Tim Tams on Amazon worked out to be more than 85 per cent more expensive than simply buying a standard pack from Woolworths. Allen’s Red Frogs in a 1.3-kilogram bag from Officeworks was 17 per cent more expensive per gram than the regular size from Woolworths. A 100-pack of Chupa Chups at Officeworks cost 57 cents each – more than double the 25 cents per Chupa Chup available in a standard 25-pack at Woolworths.

The lesson is clear: bigger packaging does not automatically mean better value. The only way to know for certain is to check the unit price – the cost per 100 grams, per litre, or per item – which is displayed on supermarket shelf labels and should always be your reference point before buying.

Is a Costco membership worth it?

Choice’s spot check of 18 bulk items at Costco found that every single product was cheaper than the best unit price available at Coles or Woolworths. For regular bulk buyers, the $65 annual membership can pay for itself very quickly – particularly if cleaning products, paper goods and pantry staples are on your regular shopping list.

The caveat is that Costco has 15 stores across Australia, so you need to be within reasonable driving distance of one. Home delivery is now available through DoorDash, but Choice’s research found prices on third-party delivery platforms can be as much as 40 per cent higher than in-store prices – which would wipe out most of your savings before you have unpacked the car.

Three questions to ask before buying in bulk

Before you load up the trolley, run through this quick checklist:

• Will I actually use all of this before it expires? Bulk buying works brilliantly for long-life pantry staples. It works less well for products with shorter shelf lives – particularly anything fresh or refrigerated.
• Do I have somewhere to store it? A 64-roll pack of toilet paper is a genuine bargain until you have nowhere to put it. Storage space is a real consideration, particularly for those who have downsized.
• Am I buying this because I need it, or because the size makes it feel like a deal? The giant jar of Nutella is only a bargain if you were going to buy Nutella anyway and you are not going to eat it all in a week.

Bulk buying can be one of the simplest and most effective ways to reduce your grocery bill – but only on the right products. Non-perishable household staples, cleaning products and personal care items are where the genuine savings live. Snack foods and confectionery in bulk are frequently more expensive than their standard supermarket equivalents, not less.

Check unit prices before you buy, shop around beyond the major supermarkets, and factor in any delivery costs when buying online. And if you’re near a Costco, the aluminium foil alone might just justify the membership fee.

Research sourced from Choice Australia’s bulk buying price analysis.