Self-catering is assumed to be the cheaper option, and it usually is, though not for the reasons most people expect. The saving concentrates in particular meals rather than spreading evenly.
Breakfast is where the difference is largest
A hotel breakfast carries the cost of a service operation: staff, opening hours, waste from a buffet and a dining room that exists solely for that hour.
The same food bought from a shop and prepared in an apartment costs a fraction of that, and the gap is proportionally the widest of any meal in the day.
A party eating breakfast in rather than out recovers a meaningful share of the accommodation difference before the day has properly begun.
Drinks compound quietly
Bar and restaurant margins on drinks are substantially higher than on food, which is why a modest bar bill can exceed the cost of the meal beside it.
Buying wine, beer or soft drinks from a shop and having them at the property removes that margin entirely, and the effect over a week is larger than most people estimate.
This is where self-catering families typically find their saving, rather than in elaborate home-cooked dinners that consume an evening.
Cooking every meal rarely happens
Holiday behaviour does not match the plan. People are out during the day, tired in the evening, and the local food is part of why they came.
A realistic pattern is breakfast in, lunch improvised, and dinner out several times a week, which is still a substantial saving without pretending the kitchen replaces restaurants.
Budgeting on that basis rather than on full self-catering produces a figure that survives contact with the actual holiday.
The first shop costs more than expected
An empty kitchen requires oil, salt, coffee, condiments and cleaning materials before a single meal is made, and none of that is consumed fully within a week.
On a short stay this initial outlay can absorb much of the theoretical saving, which is why self-catering works better over a fortnight than over a long weekend.
Properties that provide a starter supply of basics remove the problem, and it is worth asking before booking rather than discovering it on arrival.
Location changes the arithmetic
An apartment within walking distance of a supermarket is a different proposition from an isolated cottage where every forgotten item is a drive away.
In small coastal villages the only shop may be a convenience store with resort pricing, in which case cooking at home saves considerably less than expected.
Checking what food shopping actually exists nearby is therefore part of assessing the property, and it matters more than the quality of the oven.