Shared expense guide
Split costs unequally.
Keep the math clear.
Different shares can make sense for different rooms, different purchases or different contributions. Choose the rule together, then make sure the shares add up to the whole bill.
Equal, percentage or exact amounts?
| Method | What stays fixed | Example |
|---|---|---|
| Equal | The number of people | $120 across 3 people: $40 each |
| Percentage | Each person’s proportion | $120 at 50 / 30 / 20%: $60 / $36 / $24 |
| Exact amounts | Each person’s amount | $120 as $70 / $30 / $20 |
Percentages change the amounts when the total changes. Exact amounts do not: you’ll need to agree on who covers any increase. Avoid calling a method “fair” without checking that the people paying agree.
Example: a $428.60 shared purchase
Four people agree to contribute 40%, 30%, 20% and 10%. Multiply the total by each percentage divided by 100.
$428.60 × 40 ÷ 100 = $171.44
| Person | Percentage | Share |
|---|---|---|
| Person 1 | 40% | $171.44 |
| Person 2 | 30% | $128.58 |
| Person 3 | 20% | $85.72 |
| Person 4 | 10% | $42.86 |
| Total | 100% | $428.60 |
The percentages must total exactly 100%. A set that adds up to 90% leaves part of the expense unassigned; a set that adds up to 110% overcharges the group. Our calculator flags this instead of silently changing your agreement.
Use exact amounts when the amounts are the agreement
For a $300 group gift, one person might offer $150, another $100 and a third $50. Enter those exact contributions. If the gift ends up costing $320, $20 is still unassigned; decide who covers it before proceeding.
The calculator shows what is left to allocate or how much you are over the total. It does not adjust someone’s contribution on their behalf.
What happens to a leftover cent?
$100 divided by three is $33.333… each. You cannot pay a fraction of a cent, so a complete split is $33.34, $33.33 and $33.33—not three payments of $33.33.
For equal and percentage splits, our calculator rounds down to whole cents first, then assigns remaining cents to the largest fractional remainders. Ties go in participant order. The displayed shares always add up to the entered total.
If you have many expenses, you can rotate who appears first or settle a combined total so the same person does not always receive a tie-break cent.
Check the final total, including agreed extras
Include taxes, tips or booking fees in the amount being split when your group has agreed to share them. If an extra belongs only to some people, calculate it separately. The tool works in two-decimal currencies and does not fetch exchange rates.
Open the bill-splitting calculator to try equal shares, percentages or exact amounts. No account is required, and names and amounts stay in your browser.