How to split bills based on income, with a calculator
Split shared bills fairly by income. The simple formula, worked examples for couples and roommates, and a free calculator that finds each person's share.
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A 50/50 split feels fair until one person earns twice as much as the other. Then the same rent takes a small bite out of one paycheck and a huge one out of the other.
Splitting bills based on income fixes that. Everyone pays the same percentage of what they earn, so shared costs hurt everyone equally. This guide shows exactly how it works, with worked examples, and the income calculator finds your own numbers in seconds.
The formula for splitting bills by income
The whole method fits in two steps:
- Find each person’s percentage: their income divided by the combined income.
- Apply it to every shared bill: the bill multiplied by that percentage.
Example: you earn 6,000 a month and your partner earns 4,000. Combined, that is 10,000.
- Your share is 6,000 ÷ 10,000 = 60%
- Your partner’s share is 4,000 ÷ 10,000 = 40%
If your shared bills come to 3,000 a month, you pay 1,800 and your partner pays 1,200. Each of you puts in 30% of your income, which is what makes it feel fair.
Worked example: a couple’s monthly bills
Here is a typical month for a couple with a 60/40 income split:
| Bill | Total | You pay (60%) | Partner pays (40%) |
|---|---|---|---|
| Rent | 2,000 | 1,200 | 800 |
| Utilities | 250 | 150 | 100 |
| Groceries | 600 | 360 | 240 |
| Internet | 70 | 42 | 28 |
| Total | 2,920 | 1,752 | 1,168 |
You do not need to split every single bill. Many couples work out the monthly total once, then each transfers their share into a joint account or to whoever pays the bills.
Worked example: three roommates with different incomes
The same formula works for any number of people. Three housemates earn 4,500, 3,000 and 2,500 a month, so the combined income is 10,000:
- Housemate A pays 45%
- Housemate B pays 30%
- Housemate C pays 25%
On a 400 utility bill that is 180, 120 and 100. Roommates more often split rent by room size than by income, but some households prefer income splits for utilities and groceries. Our guide to splitting bills with roommates covers both.
Gross or take-home pay?
Pick one and use it for everyone. Take-home pay is usually fairer, because tax, pension and student loan deductions can differ a lot between two people with the same salary.
- Irregular income? Use an average of the last 3 to 12 months, and review it twice a year.
- Bonuses? Most couples leave them out of the monthly split and decide separately what to do with them.
- One person not earning? An income split would put every bill on one person. Many couples in this situation pool their money instead, which is covered in how to split bills as a couple.
Income split, 50/50 or something in between?
| Approach | How it works | Works well when |
|---|---|---|
| 50/50 | Every bill split in half | Incomes are similar |
| By income | Each pays the same percentage of their income | Incomes are very different |
| Hybrid | Fixed bills by income, fun spending 50/50 | You want fairness without tracking everything |
There is no wrong answer. The best split is the one you both agreed to out loud, rather than the one that happened by default.
Keep track of an income split in Half Tab
Once you know your percentages, Half Tab keeps the running balance for you. Make a group for your household, add each bill with a percentage split (for example 60% and 40%), and the app shows who owes what at any point. If one person pays the rent and the other pays the groceries, Half Tab works out the single transfer that evens it out at the end of the month.
Need a quick answer instead? The split bill calculator has the same income mode.
Frequently asked questions
What is the formula for splitting bills by income?
Each person's share is their income divided by the combined income. Multiply that percentage by the shared bill. With incomes of 6,000 and 4,000, the shares are 60% and 40%, so a 3,000 bill becomes 1,800 and 1,200.
Should we use gross or take-home pay?
Either works, as long as everyone uses the same one. Take-home pay is usually the fairer choice, because it is the money each person actually has to spend.
Is splitting bills by income fair?
Many couples and housemates find it fairer than 50/50 when incomes are very different, because everyone gives up the same proportion of what they earn. It is a choice, not a rule, so talk it through and review it when incomes change.
How do I split bills with my spouse using a calculator?
Choose Split by income in the calculator on this page, enter both monthly incomes and the shared bill total. It shows each person's percentage and amount, rounded so the parts add up exactly.
