Finding the cheapest supermarket is less useful than knowing which shop gives you the lowest total for your own basket. This practical UK grocery price comparison guide shows how to compare everyday essentials, separate genuine savings from temporary promotions, and build a repeatable shopping-list calculator using prices you check today.
Overview
There is no permanent answer to the question, “Which is the cheapest supermarket in the UK?” Prices vary by product, pack size, location, loyalty scheme, delivery method and promotion. A supermarket with a low price on milk may not be the best choice for toiletries, while a larger shop can appear cheaper per item but cost more because of waste or unused quantities.
A useful grocery price comparison therefore starts with a fixed basket. Choose the products you buy regularly, record comparable pack sizes, and compare the total rather than relying on a single headline offer. Your basket might include:
- Milk, bread and eggs
- Pasta, rice, tinned food and cooking ingredients
- Fruit, vegetables and other frequently replaced fresh items
- Toilet roll, washing-up liquid and laundry products
- Toothpaste, shampoo and other household or personal-care essentials
Keep food and non-food items in separate subtotals if you want to understand where your money is going. It is also sensible to record the standard price, any loyalty price, the required membership or app, and whether the offer has a quantity limit. A discount is only relevant if you qualify for it and can use the quantity before it expires.
For a broader weekly routine, use our UK supermarket offers tracker alongside your basket. It can help you note promotions without allowing an offer to dictate what you buy.
How to estimate your grocery total
Use a simple line-by-line calculation. For each item, record the price you would actually pay, then multiply it by the number of packs or units required:
Item cost = price per pack × quantity
Add every item to produce the basket total:
Basket total = item 1 cost + item 2 cost + item 3 cost + …
To compare supermarkets fairly, use the same basket and the same shopping assumptions at each store. A basic comparison table can look like this:
| Item | Required quantity | Supermarket A | Supermarket B | Supermarket C |
|---|---|---|---|---|
| Semi-skimmed milk | __ | £__ | £__ | £__ |
| Bread | __ | £__ | £__ | £__ |
| Eggs | __ | £__ | £__ | £__ |
| Pasta | __ | £__ | £__ | £__ |
| Toilet roll | __ | £__ | £__ | £__ |
| Total | £__ | £__ | £__ |
When pack sizes differ, compare the unit price where it is available. For example, compare the cost per litre, kilogram, 100 grams, wash or individual roll rather than comparing two shelf prices directly. Unit pricing is particularly helpful for rice, pasta, cleaning products, nappies and toiletries.
Remember to include costs outside the shelf price. For an online order, add the delivery charge, delivery pass allocation or minimum-spend requirement where relevant. If you would make a separate journey to collect one discounted item, include a realistic travel cost or ignore the item-specific saving. The cheapest shelf price is not automatically the cheapest overall purchase.
Inputs and assumptions
Your comparison is only as reliable as the inputs. Before checking prices, write down the rules you will follow:
- Brand choice: decide whether you are comparing own-brand products, named brands or an acceptable substitute. Do not compare a premium branded item with a basic own-brand item and call the difference a supermarket saving.
- Pack size: use matching sizes where possible. If they differ, use the unit price and check whether buying the larger pack creates waste.
- Quality requirements: note dietary, allergy, ethical, preparation or household requirements before looking at price.
- Loyalty pricing: record loyalty-card prices separately from non-member prices. Include only discounts available to you under the store’s stated conditions.
- Promotion limits: check whether a multi-buy, coupon or reduced price applies to the quantity you need. Do not assume that buying more is cheaper if you will not use it.
- Availability: mark unavailable items rather than silently substituting a different size or brand. Substitution can change the comparison.
- Timing: record the date and time of the check. Grocery prices and promotions can change, so an old result should not be treated as a current ranking.
For a realistic household budget, also track food waste. A slightly higher-priced pack that is fully used may provide better value than a cheaper larger pack partly thrown away. The same principle applies to toiletries and cleaning products: calculate the cost of the quantity you actually consume, not just the number printed on the label.
Coupons, cashback and loyalty points can reduce the effective cost, but keep them as a separate layer. First compare the shelf or checkout total; then apply discounts that you can genuinely claim. Our guide to stacking coupons, cashback and loyalty points explains how to check combinations without relying on incompatible offers.
Worked examples
Imagine a shopper creates a five-item basket and enters the current prices from three supermarkets. The basket contains one unit of each item, but the shopper needs two packs of pasta. The calculation for Supermarket A would be:
Milk + bread + eggs + (pasta × 2) + toilet roll = basket total
The shopper then repeats exactly the same calculation for Supermarkets B and C. If one store has a lower basket total but requires a delivery fee, the fee is added before the final comparison. If one item is unavailable, the shopper records a like-for-like substitute and flags the result as an estimate rather than presenting it as a precise total.
A second useful calculation is the saving against your usual shop:
Saving = usual basket total − comparison basket total
Saving percentage = saving ÷ usual basket total × 100
Use this only when the baskets are genuinely comparable. A lower percentage achieved by removing fresh produce, choosing a smaller pack or buying a product you would not normally use is not a meaningful saving.
You can also compare a split shop. For example, buy food at the store with the lowest food subtotal and toiletries where the non-food subtotal is lower. Before doing this, add delivery, travel and time costs. If the combined saving is small, one convenient shop may be the better budget decision.
For current supermarket offers, compare the basket with the promotions listed in our UK grocery deals guide. Treat every promotion as an input to verify, not as a reason to buy an unnecessary product.
When to recalculate
Recalculate your grocery price comparison whenever the inputs change. A practical schedule is to refresh your core basket weekly if you actively shop promotions, or monthly if you mainly buy stable own-brand essentials. Recheck sooner when your household changes, your usual products are unavailable, a loyalty price expires, or you move to a different delivery area.
Update the comparison after a notable change in pack size, recipe, dietary requirement or shopping frequency. Seasonal products may need their own basket because availability and value can differ from your regular list. Keep previous totals so you can see whether a claimed deal actually improves your household’s cost over time.
To make the process quick, save a spreadsheet or notes template with your regular products, quantities, unit measurements and supermarket columns. On each update, change only the prices and promotion conditions. Finish by choosing the cheapest practical basket, checking your cupboards first, and removing anything you do not need. That final step is often more valuable than chasing a small discount on an extra item.
