Spendthrift Spendthrift

Split expenses between any group, exactly.

One bill, a whole flat's month, or a trip. Enter the amount and the people, and every share is exact, with nothing left over.

The right tool depends on what is being split.

Three shapes of the same problem

This calculator above splits any single amount equally among a group. Two situations need something more specific.

Splitting rent, by room

Rooms are not identical, so an equal split is often wrong. Weight each room by size or a shared score, and rent follows exactly.

Split rent app

Splitting with the same person, every week

A one-off calculator is not enough for a couple or a household that shares expenses constantly. That needs a ledger, not a page you reload.

Budget app for couples

A group is not one rule.

How an expense divides

Equally, by share, by percentage, by exact amount, itemised, or not shared at all. Every expense inside a group can use a different one.

SIX WAYS TO SPLIT ONE EXPENSE Equally Four at dinner, one bill By share You brought a guest, so you are two of five By percentage Agreed proportions, for income or anything else By exact amount You say the numbers, we check they add up Itemised Line by line, and some lines belong to one person Not shared It is yours. It never enters the split at all A group is not one rule. Every expense in it can use a different one.

A group is not one rule.

One expense can be split six different ways, and every expense inside a group can use a different one.

ONE BILL. THREE LINES. THREE DIFFERENT RULES. THE BILL ₹4,800 Shared plates equally, four ways ₹2,400 Two bottles of wine the two who drank ₹1,600 One dessert Asha, on her own ₹800 WHAT EACH PERSON PAYS Asha ₹1,850 Vikram ₹1,150 Meera ₹950 Dev ₹850 Adds back to the bill ₹4,800

One bill. Three lines. Three different rules.

Shared plates equally, the wine between the two who drank it, the dessert to the person who ordered it. The four shares add back to the bill.

WHERE THE RULE LIVES On the expense, not the group Every expense carries its own rule, so one group can use six. It suggests, never decides The rule defaults to the one this group used last time. Changeable afterwards Change it a week later and only that expense recalculates. Everyone sees which was used The rule is written on the expense, in words. Nobody has to agree one rule for a whole group before the group can be used.

Where the rule lives.

The rule sits on the expense rather than the group, defaults to the one the group used last, and can be changed later without disturbing anything else.

Why this stays free.

Splitting a bill is free for everyone, permanently, including people who never install the app. Nothing you type here is sent anywhere: the arithmetic runs in your browser, using the same largest-remainder method described on the split calculator, so shares always add up exactly.

What Spendthrift itself adds, beyond this page, is the other half of the sum: when a shared expense is paid, the payer's own share flows into their budget as real spending, and the rest is recorded as money owed back, automatically. The budgeting method and the group splitting method had never done this together, because they had always come from separate companies with separate databases. See the home page for that sum, or the full money flow chart.