A cheaper offer across town is worth the drive only when the full trip costs less than the money it saves on your whole basket. Count fuel or transit, parking, extra time, and anything you still need to buy elsewhere before you change your route.
Start with the saving on the full list
A weekly offer can make one item look like a clear win. That is rarely enough information to choose a store.
Write down the price difference for every item you would actually buy there. If coffee is €3 cheaper but the rest of your list costs €6 more, the cheaper coffee has made the basket more expensive. The useful number is the total at each store, not the biggest discount in the leaflet.
For a two-store plan, compare:
- Your usual one-store basket total.
- The combined total for the first and second store.
- Any items that remain unmatched or must be bought somewhere else.
A €9 lower total is a real starting point. A €1.20 saving usually leaves little room for travel costs or a delayed evening.
Weekly offers also have limits. Check pack size, loyalty-app requirements, valid dates, and whether the offer applies to the exact product you need. A large bag of detergent may be cheap per kilogram and still be the wrong purchase if you need milk, vegetables, and dinner ingredients today.
Put a cost on the extra trip
Driving has a cost even when you do not notice it at the pump. For a quick estimate, include fuel, parking, and wear on the car. If you already track your vehicle costs, use your own per-kilometre figure. Otherwise, start with fuel and treat the rest as a caution margin.
Say the second store adds 10 km round trip. At 7 litres per 100 km and €1.80 per litre, fuel for that detour is about €1.26. Add paid parking, if relevant. If the basket saves €3, the cash difference is already small before you account for time.
Public transport has the same logic. Add the fare if the trip requires one, plus the practical cost of carrying groceries home. Walking or cycling can make a nearby second stop attractive, especially when it sits directly on your normal route.
Distance alone does not settle it. A store 1.8 km farther away may be easy to reach after work, while a closer shop involves a congested road, a hard-to-find parking space, and a long queue. Is an Extra 1.8 km Worth a Lower Grocery Basket Total? explores that tradeoff in more detail.
Give your time a realistic value
The extra stop costs time: turning off your route, parking, finding items, paying, and getting home. Use the time you actually expect, not the shortest map estimate.
If a second store adds 22 minutes and saves €2.50, ask whether you would choose that exchange on a busy Thursday. You may be happy to do it on Saturday morning, when the same €2.50 feels like a useful saving. The right answer can change by day, even with identical prices.
Set a simple personal threshold. For example, you might decide that a separate stop needs to save at least €5, or at least €10 when you are driving out of your way. A store on the route home gets a lower threshold because the added time is smaller.
This is not a rule about being disciplined. It is a way to stop a bright weekly-offer sticker from deciding your schedule for you.
Watch for the incomplete-basket trap
A cheap deal can pull you to a store that does not cover enough of the list. You then pay for a second stop anyway, perhaps at your usual shop, where the remaining items cost more.
Before leaving, divide your list into three groups: items the offer store has at a good price, items it has at an acceptable price, and items you still need elsewhere. If most of the basket belongs in the third group, build the plan around the store that covers the most, then add one targeted stop only when the saving clears your threshold.
This matters most for offers on a single staple, such as coffee, chicken, or detergent. A discounted item can belong in a worthwhile plan. It does not automatically make that retailer the best place for the whole shop. For another example, see What Happens When a 30% Discount Covers Only Half Your Grocery List?.
Compare two plans before you go
Use two columns on your phone or a piece of paper.
Plan one is your convenient complete shop. Add its basket total and the normal travel you would make anyway.
Plan two is the offer store, plus any second stop. Add both basket totals, the extra distance, parking or fare, and the extra time. Then subtract those extra costs from the basket saving.
For example, a two-store basket might be €8 cheaper. If the added drive costs €1.50 and the extra stop feels worth €3 of your time, the practical saving is €3.50. That may still be worthwhile. If the basket saving is €3, the convenient one-store plan wins.
Check the weekly offer one last time before leaving. Then choose the plan that saves enough for the route you are actually taking, rather than the deal that looks cheapest in isolation.
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