There is no single cheapest supermarket in the UK for every household or every week. The most useful answer comes from comparing your own basket, including pack sizes, loyalty-card prices, special offers, travel and delivery costs. This guide shows how to build a repeatable supermarket price comparison, estimate the real cost of a weekly shop and identify when switching stores—or changing what you buy—could make a meaningful difference.
Overview
Aldi, Lidl, Tesco, Asda, Sainsbury’s, Morrisons, Waitrose and Ocado all use different ranges, pack sizes, promotions and shopping models. A supermarket that looks cheaper for cupboard staples may not be the best choice once you add fresh food, branded products, delivery or a car journey.
Rather than relying on a general ranking, compare a standard basket that reflects your household. Include the products you buy regularly, record the price and pack size, then calculate the cost per unit. Repeat the exercise at a sensible interval because prices, promotions and loyalty offers change.
Your comparison can answer several practical questions:
- Which supermarket offers the lowest total for your usual basket?
- Does a loyalty-card price change the result?
- Is a multibuy worthwhile for the quantity you actually use?
- Will delivery, fuel or a second shop remove the apparent saving?
- Would buying own-brand or changing pack size reduce the total further?
For a broader way to record offers and prices, see the UK Grocery Savings Tracker. It can complement a personal basket comparison without replacing it.
How to estimate the cost of your weekly shop
Start with a list of around 20 to 40 products that you buy frequently. A useful basket should cover the categories that drive your spending, such as fruit and vegetables, meat or alternatives, dairy, bread, cupboard staples, frozen food, household items and toiletries.
1. Define the product carefully
Write down the specification before checking prices. For example, record “500g dried pasta”, “four pints of semi-skimmed milk” or “one litre of branded washing detergent”, rather than simply “pasta”, “milk” or “detergent”. This prevents a cheaper price from being mistaken for a cheaper equivalent.
2. Compare like for like
Record the selling price, weight or volume, brand, variety and number of items in the pack. Where exact matches are unavailable, label the comparison as approximate. A supermarket’s own-brand product may be good value, but it should be compared separately from a branded product rather than treated as an identical item.
3. Use unit prices
Calculate the unit price when pack sizes differ:
Unit price = item price ÷ weight or volume
For instance, a hypothetical 750g pack priced at £1.80 costs £2.40 per kilogram. A 1kg pack priced at £2.20 costs £2.20 per kilogram, so the larger pack is cheaper per kilogram even though its shelf price is higher. Check whether you will use the extra quantity before choosing it.
4. Add the complete shop cost
For each supermarket, add the selected item prices and any unavoidable costs:
Real shop cost = basket total + delivery or collection fee + travel cost − applicable savings
Travel cost does not need to be exact to be useful. You can compare the extra distance, parking charge or public transport fare with the expected saving. If you already pass a supermarket during another journey, its additional travel cost may be close to zero.
Inputs and assumptions
A fair comparison depends on consistent inputs. Keep a simple table with these columns:
- Product and required specification
- Supermarket
- Brand or own-brand level
- Pack size
- Standard price
- Loyalty-card or app price
- Offer conditions
- Unit price
- Notes on availability or substitutions
Loyalty prices: Record them separately from the standard price and confirm whether you qualify for the relevant scheme. If the saving requires an account, app or card, include that condition in your notes. Do not assume every product in a promotional section qualifies.
Multibuys: Apply a multibuy only if you would buy the stated quantity without the offer and can store or use it before it deteriorates. The correct comparison is not always the cheapest price per item; it is the lowest cost for the quantity your household needs.
Fresh food: Weights and quality can vary, so compare similar pack sizes and note whether an item is loose, pre-packed or prepared. A lower price is less useful if it creates waste that you would not otherwise have.
Substitutions: If a product is unavailable, record the replacement rather than silently changing the basket. This makes the result easier to audit when you repeat it.
Delivery and collection: Add the fee that applies to your chosen time slot. A delivery minimum or service charge may also affect a small shop. If you split the basket between supermarkets, count the cost of every trip, order or delivery.
Household preferences: Decide in advance whether your comparison allows branded products, organic options, dietary alternatives or specific quality standards. The cheapest supermarket for a basic own-brand basket may not be the cheapest for a basket with specialist requirements.
Worked examples
The following examples use invented figures to demonstrate the method, not current supermarket prices.
Example 1: comparing two basket totals
Suppose a household records a 25-item basket at two supermarkets. Supermarket A has a basket total of £62.40 and no delivery charge because the shop is collected during an existing journey. Supermarket B totals £60.90 but requires a £3 delivery fee.
Supermarket A’s real cost is £62.40. Supermarket B’s real cost is £63.90. Although B has the lower shelf total, A is cheaper for this particular shopping arrangement by £1.50.
Example 2: loyalty pricing
Imagine a basket with a standard total of £58.20. Eligible loyalty prices reduce the same basket by £4.10, producing a total of £54.10. Record both figures because the standard price is the useful comparison for someone without the scheme, while the loyalty total represents the cost for a shopper who can use it.
Example 3: a multibuy
A household needs two packs of a product during the month. A single pack costs £3.20, while an offer makes two packs £5.50. Buying two normally costs £6.40, so the offer saves £0.90 if both packs would have been purchased anyway. If the second pack is likely to go unused, the headline saving is not a genuine saving for that household.
After your first comparison, look for the largest differences rather than trying to optimise every item. A small number of regularly purchased products may account for much of the gap between baskets. Check those products first when prices or offers change.
When to recalculate
Revisit your comparison when the inputs change, not necessarily every time you shop. A monthly check is a practical starting point for a regular household basket, while a shorter interval may be useful if you rely heavily on promotions or notice frequent price changes.
Recalculate sooner when:
- Your usual supermarket changes a loyalty-price structure or offer.
- You move house or your nearest stores change.
- You begin shopping online, using delivery or switching to collection.
- Your household size, diet or preferred brands change.
- You start buying more household products, nappies, formula or pet food.
- A promotion changes the pack size or quantity you normally buy.
- You suspect that a second supermarket trip is cancelling out the saving.
Keep a monthly savings tracker with the date, basket total, supermarket, fees and notable substitutions. Compare the latest result with the previous one, but avoid treating a single promotional week as a permanent ranking. The most useful conclusion is often that one supermarket is best for your core basket, while selected offers elsewhere are worth checking before each shop.
For practical ideas on combining supermarket offers with other savings, read How to Stack UK Discounts. You can also browse current UK supermarket offers, then test any apparent deal against your own basket, unit prices and total shopping cost.
Action checklist: choose your regular basket, set clear product specifications, record standard and loyalty prices, calculate unit prices, add travel or delivery costs, assess multibuys honestly and save the result. Repeat the process when your circumstances or the supermarket’s pricing changes. That gives you a more dependable answer to “which is the cheapest supermarket for my weekly shop?” than a one-size-fits-all league table.
