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Shared expense split calculator

Share one monthly amount, such as rent, utilities or the weekly shop, between 2 and 6 people and see what each pays. You choose how to split it: equally, in proportion to income, or by percentages you set yourselves. For every person you get the amount in money and per cent and, where you enter an income, what's left of it afterwards. Everything runs in your browser.

Split one shared monthly amount between 2 to 6 people — equally, in proportion to income, or by custom percentages. Names are labels only and never enter the maths. Which method you use is a private decision; the calculator does not judge any of them. The calculation runs in your browser; nothing is stored.

How should the costs be split?

Everyone pays the same part. An income is optional — if you enter it, the calculator shows the income left afterwards.

People

What your result means

For each person you get the amount they pay, their percentage share and, if you entered an income, what remains of it. A total line checks that the contributions add back up to the shared amount. From there the reading is yours: an equal split is the simplest, an income-based one leans on what each person earns, and custom percentages put down whatever you've agreed between you.

How this calculator works

Start with one shared total, choose a method, and list 2 to 6 people. The three methods differ only in how they divide that total.

Equal: everyone pays the same amount, which is the total divided by the number of people, so each share is an even slice of 100%.

In proportion to income: each person pays in line with what they earn. Add everyone's income together, and a person covers the same fraction of the bill as they make up of that combined income. This method needs an income for every person, and those incomes have to add up to more than zero.

Custom percentages: you give each person a percentage, and their contribution is that slice of the total. The percentages have to reach 100% (to within 0.01 of a point). If they don't, the calculator flags it instead of quietly adjusting your figures, so you can fix the numbers yourself.

Where someone's income is entered, you also see what's left once their share comes off; leave it blank and that figure simply isn't shown. Nothing is made up. The working is done unrounded and rounded only for display.

Formula and variables

equal: b = K / n, a = 100 / nproportional: b = K · E / SE, a = E / SE · 100custom: b = K · a / 100left over: R = E − b (only if E entered)
K
shared total cost (one monthly amount)
n
number of people (2 to 6)
E
a person's net income (optional, except for the proportional method)
SE
sum of all people's incomes
a
a person's share, in per cent
b
a person's contribution to the total
R
income left after the contribution

Worked examples

Example 1: equal split, with a look at the income left

Example inputs
MethodEqual
Shared cost€800.00
Person A – income€2,400.00
Person B – income€1,600.00
Example results
Person A – contribution€400.00
Person A – share50%
Person A – income after€2,000.00
Person B – contribution€400.00
Person B – share50%
Person B – income after€1,200.00

With the equal split each person pays €800.00 / 2 = €400.00, so 50%. Because incomes are entered here, the calculator also shows what is left afterwards: A keeps €2,000.00, B keeps €1,200.00. The incomes do not change the equal split; they only explain the income left over. All figures are example assumptions.

Example 2: income-proportional split

Example inputs
MethodIn proportion to income
Shared cost€2,000.00
Person A – income€3,000.00
Person B – income€2,000.00
Example results
Person A – contribution€1,200.00
Person A – share60%
Person A – income after€1,800.00
Person B – contribution€800.00
Person B – share40%
Person B – income after€1,200.00

The income sum is €3,000.00 + €2,000.00 = €5,000.00. A pays €2,000.00 · 3,000 / 5,000 = €1,200.00 (60%), B pays €2,000.00 · 2,000 / 5,000 = €800.00 (40%). Afterwards A keeps €1,800.00 and B keeps €1,200.00. Together the contributions add back up to €2,000.00. Whether an income-proportional split suits you is your decision.

Assumptions

  • One single shared amount is split (a monthly figure in the same currency).
  • Names are labels only and never enter the maths.
  • The income-proportional method needs an income for every person; the sum of incomes must be greater than 0.
  • For custom percentages the shares must add up to 100% (to within 0.01 percentage points); nothing is normalised automatically.

Limitations of this calculator

  • Choosing a method is a private arrangement; the calculator calls no method fair, fairer or correct.
  • No maintenance, tax or legal statement; it is not a substitute for an individual agreement.
  • Only one amount is split. For a full monthly picture across several cost types, use the household budget calculator.
  • No live data; your inputs are not stored. All results are approximate and provided without guarantee.

Common misconceptions

  • Leaving out an income where the method needs it: The income-proportional split needs an income for every person, and the incomes have to add up to more than zero. Without them the split can't be worked out.
  • Custom shares that don't total 100%: With custom percentages the shares must add up to 100%. Any other total is not corrected automatically but shown as a note.
  • Splitting several bills at once: This tool splits one shared amount. For several different costs, add them up first or use a household budget view.

Frequently asked questions

Which split method is the right one?

That is your decision. The calculator treats the equal, the income-proportional and the custom-percentage split alike and calls none fair or correct. It only works out what the chosen method means for each person.

Do the names enter the calculation?

No. Names are labels only, so you can tell the rows apart. Only the shared total, the incomes and the shares enter the maths.

Do I have to enter an income for every person?

Only for the income-proportional method: there an income is required for each person, and the sum must be greater than 0. For the equal split and for custom percentages the income is optional; if you enter it, the calculator also shows the income left after the contribution.

What happens if the custom shares don't add up to 100%?

The calculator shows a note and does not compute. It deliberately does not normalise the shares automatically, so it stays clear that the input is not right yet. If the sum matches 100% to within 0.01 percentage points, it computes.

Is this a statement about maintenance or tax?

No. The calculator makes no maintenance, tax or legal statement and does not replace an individual agreement. It is a neutral calculation tool for a private arrangement.

Are my inputs stored?

No. The calculation runs entirely in your browser. No inputs are stored, sent or analysed.

Sources and further reading

Official and independent sources on this topic. The links open each website in a new tab; no content is loaded from them into this page.

Spotted an error in the calculation or the text?

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Last reviewed: 23/09/2026 · All calculations run in your browser – inputs are not stored. ·How we check our calculators