Itemized splitting
Split a bill by item, so nobody subsidizes the steak
Dividing the total by four is quick and slightly unfair to everyone who ordered a salad. Splitting by item takes about a minute longer and gets it right: each person pays for their own lines, plus their share of tax and tip in proportion to what they had.
How the arithmetic works
Three people, one check. Ana had the steak, Ben had the pasta, Chi had the salad, and they shared a bottle of wine.
| Steak — Ana | $32.00 |
| Pasta — Ben | $18.00 |
| Salad — Chi | $10.00 |
| Wine — shared three ways | $30.00 |
| Subtotal | $90.00 |
| Tax | $7.20 |
| Tip (18%) | $16.20 |
| Total | $113.40 |
The wine divides three ways at $10 each. That gives Ana $42 of the subtotal, Ben $28 and Chi $20 — so they carry 46.67%, 31.11% and 22.22% of the tax and tip respectively:
| Person | Items | Tax | Tip | Owes |
|---|---|---|---|---|
| Ana | $42.00 | $3.36 | $7.56 | $52.92 |
| Ben | $28.00 | $2.24 | $5.04 | $35.28 |
| Chi | $20.00 | $1.60 | $3.60 | $25.20 |
$52.92 + $35.28 + $25.20 = $113.40, the printed total exactly. Split the same check evenly and Chi would have paid $37.80 — $12.60 more than they owe, for a salad.
Why this is annoying by hand
The percentages are fiddly
Every shared item changes everyone's proportion, so one late addition means recalculating all of it.
Rounding does not behave
Three people and a tax bill ending in an odd cent will not divide cleanly. Somebody has to absorb it, and by hand that somebody is usually whoever is holding the calculator.
People remember wrong
Asking the table what they had produces a different answer from asking the receipt. Letting each person tap their own lines removes the argument.
It happens at the worst moment
The bill arrives when everyone wants to leave. Doing arithmetic on a napkin while six people wait is the actual problem.
Let everyone claim their own
Scan the receipt, share the link, and watch the totals settle themselves.
Split a bill by itemGroceries instead of a restaurant? Splitting a grocery bill with real tax rates