Who pays for the wine

Somebody at the table did not drink. They had the tap water, they had one course, and they have spent the last hour listening to a discussion of a second bottle they did not order. The bill arrives face down. Someone turns it over and says the line that closes the subject before it can open. "Shall we do it evenly."

An even split reads as the absence of a decision, which is why it is so hard to argue with. It is a decision. It moves the cost of the group's most expensive appetites onto everybody at the table, and buys in return a table where nobody has to price their own evening out loud. Most of the time that is a good trade. Sometimes it is not, and the dinners that end quietly are the ones where nobody had the language to say which of the two they were in.

Four conventions are in general use. Most arguments about a bill are two people running different ones.

The even split

It is fast, and it spares everyone the declaration. The person who ordered the cheapest thing on the menu is not made to announce it, and the person who ordered the second bottle is not made to defend it. In a group that eats together often it costs nothing, because the subsidy rotates. Tonight you drink and somebody else drives.

It stops working the moment the difference stops rotating. Two people three rounds in and two people on tap water is not a rotation, it is a transfer, and the person on the losing side can see it, because they are reading the same bill. The convention's whole defence is that the gap is too small to be worth naming. When the gap is a third of the total, the defence is gone and the convention carries on anyway.

The drinkers' carve-out

Take the alcohol off the top, divide it between the people who drank it, split the food evenly. That is most of the asymmetry gone. Drink is where the spread lives: ordered late, ordered by the round, priced by the bottle, printed as its own block of lines. Nothing else on a restaurant bill varies that much between two people who ate the same meal.

The cost is not arithmetic, it is sequence. Somebody has to say it out loud, and whoever says it becomes the person who is counting. The non-drinker is the worst placed to raise it, which is why they are usually the one left to. From the person who ordered the wine, "take the bottles off and we'll cover those" is generosity. From the person on tap water, the same instruction is a complaint.

Itemising

Assign every line to whoever ordered it. What it buys is a number nobody can argue with, which in a group of near-strangers is worth more than the money.

What it costs is that the evening becomes a reconciliation, and everyone's choices get priced in front of each other. It also scales badly downwards: recovering four euros from a friend costs more than four euros, every time. It earns its place when the bill is long, the group is large, and the people in it are not close — a stag weekend, a fortnight in a villa, eleven people of whom four are somebody's colleagues. There the accuracy is the courtesy.

The quiet subsidy

The fourth convention is the most common and the least discussed, because it is never proposed. It is defaulted into. One person notices the asymmetry, works out that raising it would cost more than absorbing it, and absorbs it. Nothing is said. The dinner ends well, once.

Starling Bank's 2023 survey of two thousand UK adults found that 46% of people owed money by friends or family were too embarrassed to ask for it, that getting it back took more than two months on average, and that 17% had begun to resent the person who owed them. The mechanism is asymmetry of memory: being owed is remembered, owing is not. Some people never bring it up at all, and carry a resentment that outlasts the friendship.

Three harder cases

The vegetarian who had the €9 salad and pays a share of somebody's €34 steak is the standard example and the weakest of them, because on any single night the difference is small. Repetition is what makes it hurt. The response is not to itemise this dinner, but to notice, around the tenth, that the same person has been on the subsidising side of all ten, and to change the convention rather than the maths.

Bottles ordered "for the table" are the genuinely hard case, because shared is a claim about intent rather than about consumption. Two bottles arrive for eight people and four of them drink both. Nobody lied. The order really was placed on behalf of the table, and no line on the bill records what happened next. Only a convention rescues this one: either shared bottles stay shared however they get finished, or drink is per-person, and the table decides which before the second bottle.

Arriving at nine to a table that sat down at seven is the clean case, and still the one groups get wrong most often. The pool was agreed before you got there, and the agreement is doing the work. The fix is one sentence on arrival.

Is everyone going to split the loo roll

This is the objection every fairness argument runs into, in one form or another: if the wine gets its own line, then so does the loo roll, the lights, and the time each person spent in the kitchen.

Fairness has a granularity floor, and everything worth doing happens above it. Three tests put an asymmetry above the line. It is large. It is visible on the bill. It is attributable to named people without anyone having to reconstruct the evening from memory. Wine clears all three. The loo roll clears none, and the only way to lift it above the line is a turnstile on the bathroom door.

Naming the two or three asymmetries above the floor is what saves you from counting the things below it. Groups that end up counting everything are usually groups that declined to name the one large thing, and then had to relitigate every bill after it.

What to say, and when

Three sentences do nearly all of this work, and none of them name anybody. Before the menus are collected, from whoever is nearest the middle of the table: "Are we splitting evenly, or doing drinks separately?" From a drinker, once the second bottle is on its way: "Put the wine on us at the end." From somebody arriving late, in the first minute rather than the last: "I will get mine separately."

All three are logistics when they are said early and accusations when they are said over the bill. The words do not change. The clock does.

Good to know

None of this is enforceable, and none of it survives being introduced late. If nothing was agreed before ordering, the cheapest option left is to split evenly and set the convention next time.

There is also a floor below which the exercise costs more than it recovers. If a month of disputed dinners comes to less than one of those dinners, the conversation is the expensive part.

No tool does the social half. Split states the figure and shows how it got there, which is the half people argue about least. It holds no opinion about which convention your table should use, it does not check with a bank and cannot, and settling up is a tap that records what two people already did.

Agreeing a convention takes about eleven seconds while the menus are still on the table. A Split room is a link, and it will keep count without joining the argument.