Agree on the method before the math
An equal split assigns half the shared costs to each person. An income-based split assigns costs in proportion to take-home income. Neither method determines fairness by itself. Unpaid caregiving, separate debts and access to money may change what you agree to share.
- Choose the same time period for income and costs.
- Enter only expenses you have agreed are shared.
- Choose a method and enter amounts already contributed toward those expenses.
A worked example
If A brings home $3,000 and B brings home $2,000, their combined take-home income is $5,000. A’s proportion is 60% and B’s is 40%. For $2,400 in shared bills, A’s share is $1,440 and B’s is $960. An equal split would be $1,200 each.
Amounts already paid reduce each person’s remaining contribution. A negative remaining amount is an overpayment to the shared bill pool. This tool does not decide who should reimburse whom: first check whether the bills themselves are fully paid.
Keep the conversation practical
Write down what counts as shared, which period you use and when you will revisit the agreement. Round only the final contributions; the second share is the total minus the first so the two shares reconcile to the cent.
Keep planning
Sinking fund calculator · Bill frequency calculator · Paycheck budget calculator · Annual vs. monthly subscription · Emergency buffer calculator
Method reviewed November 1, 2026. Educational arithmetic; no individualized financial recommendations.