Hong Kong supermarket unit prices: compare packs and bundles

Why the cheapest shelf price may cost more

A HK$24 packet and a HK$32 packet are not comparable until you know what each contains. If the smaller packet holds 300g and the larger holds 500g, the first costs HK$8 per 100g and the second HK$6.40 per 100g. The larger packet has a higher checkout price but a lower unit price. This is the central supermarket comparison: pay attention to the amount of equivalent usable product, not just the number in the largest font on a shelf label.

The Hong Kong Consumer Council has called for consistent unit-price display to make cross-brand and cross-pack comparisons easier. Its Online Price Watch also shows prices from online retailers, although the amount paid at your chosen store and time can differ. A price-watch result is a useful reference, not a promise that a product remains in stock or that a delivery promotion applies to your basket.

This guide teaches a repeatable calculation. It does not claim to rank the cheapest supermarket today. Use the supermarket deals category to discover current offers, then compare like-for-like product sizes and the actual checkout amount. All worked prices below are illustrative. A shopper should confirm the current product label, expiry date and offer terms before paying.

Choose one unit before comparing two products

For solid foods, choose a common weight such as 100g or 1kg. For drinks and cleaners, use 100ml or 1 litre. For items sold individually, use one usable piece. Divide the payable price by the quantity, then multiply by the unit you want to display. A 750g bag for HK$45 costs HK$6 per 100g because 45 ÷ 750 × 100 = 6. A 1kg bag for HK$58 costs HK$5.80 per 100g. The arithmetic only helps if the two bags are substitutable for your purpose.

Do not compare per-pack figures when pack sizes vary. A box of 10 tissues and a box of 12 have different piece counts, while tissue sheets may also differ in ply, dimensions and number of sheets per pack. A detergent bottle can display volume, washing loads and a recommended dose; cost per 100ml may be less useful than cost per wash when the concentration differs. State the chosen unit next to the price so that a family member can reproduce the result.

Unit price is not a complete quality judgment. If two rice products have different origins or varieties, their price per kilogram answers the cost question but not whether they meet the same cooking need. Compare the same brand and specification first. When comparing alternatives, write down the meaningful difference in ingredients, quality, concentration or intended use instead of calling one an automatic bargain.

Convert bundles to the price of one usable item

A two-for-HK$30 promotion on identical 250g packs means HK$15 per pack and HK$6 per 100g. The calculation is bundle price ÷ total weight × 100. Compare that with the single-item alternative, not with a crossed-out reference price alone. If another store offers a 500g pack for HK$28, its unit price is HK$5.60 per 100g. The single larger pack is less expensive per gram even though the two-for banner may look louder.

For buy-two-get-one-free on three identical HK$18 packs, the payment is HK$36 for three packs, or HK$12 per pack. If each holds 200g, the effective unit price is HK$6 per 100g. A second-item-half-price deal on two identical HK$18 packs costs HK$27, or HK$13.50 per pack. The first bundle has the better per-pack price only if you need and can use three packs. For a shopper needing exactly two, the second offer has a smaller total bill.

Mixed-item bundles need more care. If a promotion discounts the cheaper item, pricing two different sizes as if both were the expensive item exaggerates the saving. Enter the two actual shelf prices and check which line the till reduces. If the retailer limits redemptions per customer, gives a coupon for the third item or requires a member card, those conditions belong in the calculation. A future coupon is not equivalent to a free product in the basket today.

A larger pack can be worse value

The phrase “family size” is not a unit-price guarantee. Imagine a 400g product at HK$24 and an 800g pack at HK$52. The smaller pack costs HK$6 per 100g; the larger costs HK$6.50 per 100g. Buying the large one would raise both the cash outlay and the unit price. Promotions, private-label alternatives and different pack formats can reverse the intuitive assumption that bulk always wins.

The Consumer Council has reported that larger packs and multi-buy promotions are not necessarily better value in its supermarket price analysis. Its recommendation to compare standard units supports a simple habit: calculate the cost for the quantity you actually consume, then check whether the larger pack is still cheaper. This is especially important when a product is displayed in different weight, volume or piece units across shops.

A large package may also have a hidden practical cost. If it cannot fit in your freezer, occupies scarce storage space or goes stale before use, its low per-100g price is not the price per usable gram. A pack of berries that costs 20% less per kilogram but loses a third to spoilage costs more per eaten kilogram. A bigger pack is a saving only when storage, freshness and household demand support using it.

Calculate the usable amount, not just the labelled amount

For fresh produce, the labelled kilogram may include peel, shells or trimming. If two options have different usable yields, compare cost per edible amount. Suppose Product A costs HK$40 for 1kg and you expect to use 800g; its edible cost is HK$5 per 100g. Product B costs HK$45 for 1kg and yields 950g; its edible cost is about HK$4.74 per 100g. These yields are teaching assumptions, not fixed facts about a food category. Your actual preparation method will change them.

For a discounted perishable item, the useful quantity depends on the expiry date. If a household can finish only two of four yoghurts before they spoil, a four-for-HK$40 pack effectively costs HK$20 for each yoghurt consumed. Two fresh individual yoghurts at HK$15 each would cost HK$30 total, saving HK$10 despite a higher advertised per-item rate. The same logic applies to a frozen item when you lack freezer capacity.

Avoid pretending that uncertain waste can be predicted exactly. A practical comparison is to run a best case, where everything is used, and a realistic case based on your meal plan. If the supposed bargain wins only in the best case, buy the smaller quantity unless you have a concrete plan for the excess. A bargain that changes your menu in an unwanted way is not automatically valuable.

Check what the comparison price really means

A crossed-out figure may be a regular shelf price, a recommended retail price or another stated reference. It should not be silently treated as the historical price paid by shoppers at that outlet. The Hong Kong Consumer Council has examined confusing supermarket strike-through displays and urged clearer identification of comparison prices. The safe independent test is to compare the current amount you will pay for equivalent goods rather than relying on the displayed percentage reduction.

Suppose a package is marked “HK$80, now HK$50”, while another shop sells the same size and specification for HK$48 without a sale label. The second option is HK$2 less at the moment of comparison. Whether HK$80 was once a genuine selling price does not change that immediate arithmetic. If you shop this item often, a price history can help decide whether HK$50 is unusual, but never infer a stable typical price from one screenshot.

Check the date, branch and channel. In-store and online prices can differ; a promotion may apply only to selected outlets, a membership tier or particular quantities. The Consumer Council price-watch tool provides a way to check listed online prices, but the retailer checkout remains the direct evidence for your intended transaction. If a shelf label and the scanned bill disagree, keep the receipt and raise the discrepancy with the retailer.

Delivery charges and minimum spend belong in the basket cost

A lower online unit price does not necessarily produce a cheaper basket. Imagine Store A sells your planned goods for HK$280 and charges HK$40 delivery, while Store B sells the same basket for HK$300 with delivery included. A totals HK$320; B totals HK$300. If you already need other goods from A, its delivery threshold might change the result. Compare the complete necessary basket with fees included, not a single discounted item in isolation.

Free-delivery thresholds can encourage unnecessary additions. If your basket is HK$280 and shipping is HK$40 unless you reach HK$350, adding HK$70 of things you do not need makes the total HK$350 rather than HK$320. You spent HK$30 more. Adding HK$70 of essentials you would otherwise buy soon is a different case; then the extra goods have genuine value. Separate planned purchases from items added solely to unlock a banner.

A voucher may also exclude delivery fees from its qualifying spend, or may calculate its threshold before other coupons. The order of operations matters: first identify eligible goods, then apply product or basket reductions as the retailer defines them, then add unavoidable charges. If you cannot reproduce the advertised saving at checkout, do not assume the missing reduction will be refunded later.

Membership prices and payment rewards are different layers

A member-only supermarket price can reduce the amount charged today. A card reward may be credited later and can depend on merchant coding, registration or a reward cap. Put them on separate lines. For example, an illustrative HK$100 grocery item falls to HK$90 for members. A qualifying 2% card reward on the HK$90 charged would be HK$1.80, making a potential effective cost of HK$88.20. Do not calculate 2% on the old HK$100 unless the bank terms actually say to do so.

A points programme introduces another layer. A “HK$10 voucher” that can be used only on a later HK$200 purchase is not a HK$10 reduction on today’s basket. If you expect to use it on a planned future purchase, you can record its potential value separately. If the expiry, merchant or minimum-spend restriction means you will probably not redeem it, do not count it at full value in a cross-store comparison.

Payment rewards should never drive a purchase that is unnecessary. It is also easy to double-count a bank’s advertised “up to” total when the base reward is already inside the promotional rate. Calculate the merchant payment first and the expected card return second. Keep the uncertain return distinct from the cash amount leaving your account today.

Build a fair household basket comparison

For a weekly shop, create a short mobile note with product, brand or acceptable substitute, pack size, needed quantity and the price you actually expect to pay. Write “rice, 2kg, one bag” rather than “rice offer”. Add a separate line for delivery or collection fees. If a store lacks one product, mark the substitute explicitly; do not let a smaller pack quietly replace a larger one just to make the basket total look lower.

Compare Stores A and B on the same consumption quantity. If A sells six 250ml drinks for HK$42 and B sells four 330ml drinks for HK$36, A provides 1.5 litres for HK$28 per litre, while B provides 1.32 litres for about HK$27.27 per litre. B is marginally cheaper by volume, but A may be more useful if six smaller servings reduce waste. This example shows why a fair basket comparison can produce two honest answers: cash cost for the required quantity and cost per equivalent unit.

A compact decision line might read: “A: HK$286 goods + HK$35 delivery = HK$321; B: HK$307 goods + HK$0 delivery = HK$307; same usable quantity, B cheaper by HK$14.” If one basket includes a future coupon, note it separately rather than subtracting it from the payable total. This format is readable on a phone and can be checked against the receipt later.

A five-minute check before buying

First, verify that the products have the same use, size and specification. Second, convert each payable price to the same unit. Third, calculate the bundle as a whole and check whether you will use every item. Fourth, add delivery and other unavoidable fees to the planned basket. Fifth, keep later points or card rebates separate from instant savings. These five steps are more reliable than sorting by the largest displayed discount percentage.

For expensive or frequently bought items, check the Consumer Council Online Price Watch and the current retailer product page. Price Watch can help identify another listed retailer or a different pack size; the retailer page confirms the live offer and availability for the chosen outlet or delivery address. A historical or comparison price is context, while the amount at checkout is the cost you must approve.

After the transaction, compare the receipt with the expected member and multi-buy reductions. If the till applied the wrong quantity or the promotion did not trigger, resolve it while the evidence is fresh. The aim is not to perform an elaborate spreadsheet exercise for every carton of milk. A consistent unit, a realistic basket and a quick receipt check are enough to prevent many avoidable overpayments.

• Hong Kong Consumer Council Online Price Watch ↗
• Consumer Council guide to supermarket unit pricing ↗
• Consumer Council analysis of pack sizes and multi-buy offers ↗
• Consumer Council study of strike-through prices ↗