A fair split calculator for an uneven split

Fairness is one word doing several jobs, and the sum you want depends on what is uneven. A bigger bedroom is one question, a longer drive is another, and a dinner where one person had the tasting menu and another had soup is a third.

Getting it wrong is rarely dramatic. It is the person who did the maths becoming the person who has to defend it, three weeks later, in a group chat, with the working on their phone and nowhere else. Split by Peanut holds the number so nobody has to be that person.

Which sum you actually want

If it is the rooms, the number follows floor area: measure the private rooms, leave the shared space out, and each person pays the proportion of the rent their room is of the total. That is the rent split calculator, which puts a slider beside each name for the half floor area cannot settle.

If it is the driving, the number follows distance at a rate that prices the car rather than the petrol. A fair per-kilometre figure stands in for tyres, servicing and the value the car sheds, which is why the official one sits above the pump. The mileage split calculator costs a drive that way and splits it between everyone who was in it.

If it is a bill between people, there is no calculator here and there will not be one. A figure in a form is a figure one person retypes into the group chat, which is the whole job. Open a room instead: everybody adds what they paid, and it nets down to two or three transfers instead of twenty.

Where this stops being worth it

Somebody always points out that nobody is metering the kitchen, or the lights, or the trips to the loo, and they are right to. Most households draw the line in the same place: split what one person clearly consumes, leave the shared things shared.

Knowing when to stop is the other half. A method that moves a few pounds a month costs more in bad feeling than it moves in money. Work the number out and look at the gap before deciding to run it.

When an even split still wins

It is right more often than the search results suggest: when the difference is small, when the group would rather not measure each other, and when the thing is a one-off nobody will remember.

Good to know

Split is free forever, with nothing to upgrade to. Peanut makes it to introduce people to Peanut, which is how Split gets paid for, so there is no paid tier and nothing to move behind one later.

The calculators do the weighting and the room does the ledger. It takes 158 currencies, converted at the day's rate, and holds up to twenty people. Split records a payment rather than making one. It does not check with a bank and cannot.

The uneven part is a decision, the rest is a room

Takes ten seconds. No email, no password, no download.

Start a split

Questions

Is there a calculator that splits a bill by income?
Not for a one-off bill. Income weighting lives on the rent split calculator, as a slider rather than a box asking for your pay, because it belongs to an arrangement that repeats. For a dinner it is a conversation the group has once, and the room holds what it produced.
How do you split a dinner bill when somebody did not drink?
Take the wine off the top and split it between the people who drank it, then split what is left evenly. In a room that is two expenses rather than one, which is why it survives a question a week later.
How do you split rent unequally?
Two things carry almost all of it: floor area and who is better off. Measure the rooms first, because nobody has to disclose anything to agree that part. Decide the second out loud, once, then leave it alone.