Three families, three different ways to split the same bill. The "fair" method depends on what your family values: equality of contribution, equality of sacrifice, or protection of the most vulnerable earner. There is no universally correct answer — but there is a correct answer for your family, and this calculator lets you compare them side by side.
The four methods we offer
Prorated by income divides the bill in proportion to each member's monthly income. If Grandma earns $1,800 and the household brings in $12,500 total, Grandma pays 14.4% of every shared bill. This is the method most family therapists recommend for multi-generational households because it equalizes the sacrifice — everyone gives up roughly the same share of their disposable income.
Equal per person divides the bill by the head count. Simple, transparent, and brutal to the lowest earner. We include it because some families prefer it, but it is rarely the right choice when incomes vary by more than 2:1.
Hybrid (50/50) splits the bill in half: half is divided equally per person, half is prorated by income. This is a compromise that ensures everyone contributes meaningfully without crushing the lowest earner.
Equal with income floor caps each person's share at a percentage of their income (we use 30% as a healthy ceiling). Anyone whose equal share would exceed that cap pays the cap instead; the remainder is redistributed among the higher earners. This is the safety-net method.
The politics of splitting bills
Whatever method you choose, write it down. A shared spreadsheet or a printed fridge chart prevents the slow resentment that builds when one person feels they are paying more than their share without acknowledgment. Revisit the split every January and after any income change — raises, retirements, new jobs. The fairest split today may not be fair next year.