Couples Budget Calculator
Enter both monthly incomes and your shared expenses. The calculator compares a 50/50 split with an income-based split and shows what each partner has left.
Last updated: September 23, 2026 · The calculation runs entirely in your browser.
Your numbers
Monthly values, in your preferred currency.
Result
Comparison of the two split methods.
| Item | Partner A | Partner B |
|---|---|---|
| Monthly income | — | — |
| 50/50 share | — | — |
| Income-based share | — | — |
| Left after expenses (50/50) | — | — |
| Left after expenses (income-based) | — | — |
How the income-based split works
With an income-based split, each person covers the same percentage of their own income. The share is the shared expenses multiplied by that person's income divided by the couple's total income.
Example: if shared expenses are $1,500 and the incomes are $2,000 and $3,000, total income is $5,000. Partner A covers 40% ($2,000 / $5,000) and pays $600, Partner B covers 60% and pays $900. The weight on income is identical: 30% in both cases.
50/50 or income-based?
A 50/50 split is the simplest: half each, no math. It works well when incomes are similar. When incomes are very different, though, the same amount weighs much more on the partner who earns less.
An income-based split is fairer in that case, but it needs a calculation and should be updated when incomes change. In short: similar incomes use 50/50; different incomes use income-based.
How to use the result
- pick a method and keep using it consistently instead of recalculating every month
- log shared expenses in one place so the share stays verifiable
- revisit the calculation only when an income or a fixed expense changes
- check once a month what each partner has left
The calculator gives you the share; keeping it accurate over time needs one shared place to record expenses, income, and recurring payments. That is exactly what Dunio does.
Frequently asked questions
How do you split shared expenses as a couple?
With a 50/50 split each person covers half of the shared expenses. With an income-based split, each person covers the same percentage of their own income: multiply the shared expenses by that person's income divided by the couple's total income.
What is the difference between a 50/50 split and an income-based split?
A 50/50 split divides expenses equally, so it weighs more on the partner who earns less. An income-based split makes expenses weigh the same on both incomes, so the higher earner pays more.
Does the calculator save or send my data?
No. The calculation runs entirely in your browser and no data is sent to or stored on a server.
Try Dunio
If you want to split shared expenses without redoing the math every month, Dunio keeps expenses, income, net worth, and recurring payments in one shared workspace.