Fair Share Calculator

A fair share calculator determines how much each person should contribute to shared expenses based on their income. Instead of splitting costs 50/50, it calculates proportional shares — so a partner earning 4,000 EUR contributes more than one earning 2,000 EUR, but both pay the same percentage of their income. This approach is widely considered fairer because it accounts for different financial capacities and ensures neither partner is disproportionately burdened.

The calculation is straightforward: each person's share equals their income divided by the combined household income, multiplied by the total shared expenses. For example, if Partner A earns 3,000 EUR and Partner B earns 2,000 EUR, Partner A pays 60% (3,000/5,000) and Partner B pays 40% (2,000/5,000) of shared costs. For 1,500 EUR in shared expenses, Partner A would pay 900 EUR and Partner B would pay 600 EUR. Both contribute 30% of their individual income — that's proportional fairness.

A 50/50 split is simple but only truly fair when both partners earn roughly the same amount. When there's a significant income gap, equal splitting means the lower earner pays a much higher percentage of their income, leaving them with proportionally less for personal spending and savings. For example, if expenses are 1,200 EUR and incomes are 4,000 EUR and 2,000 EUR, a 50/50 split costs the lower earner 30% of their income but only 15% for the higher earner. Proportional splitting equalizes the financial impact.

Income changes — promotions, job switches, parental leave, or reduced hours — should trigger a recalculation of fair shares. We recommend reviewing your split quarterly or whenever a major income change occurs. Simply enter the new income figures into the calculator to get updated shares. Some couples set a reminder to reassess every January, aligning with any salary adjustments. The key is that fair sharing is dynamic, not a one-time decision.

Shared expenses typically include rent or mortgage, utilities (electricity, water, internet, heating), groceries, household supplies, joint insurance policies, and shared vehicle costs. Expenses that are usually kept individual include personal clothing, hobbies, individual subscriptions, and personal gifts. The grey area — dining out together, vacations, pet costs — should be discussed and agreed upon as a couple. Use our Subscription Calculator to identify which subscriptions could be shared.

Yes, the proportional principle works for any group size. In a flat-share with three or four people, each person's share is calculated the same way: their income divided by the total group income, multiplied by total shared expenses. This is especially useful for WG (shared apartment) situations where roommates have different incomes — a working professional and a student shouldn't pay the same rent. For room-size-based splitting, try our Rent Split Calculator, which considers square meters too.

When there's a large income gap (e.g., 70/30 or more), purely proportional splitting sometimes feels unfair to the higher earner, who might pay for most expenses. Some couples set a cap — for example, the higher earner pays maximum 65% regardless of income ratio. Others use a hybrid approach: split fixed costs proportionally but maintain equal spending on discretionary items like holidays. Open communication about expectations is more important than the exact formula. Our calculator gives you the proportional baseline, which you can then adjust together.

Manually calculating and tracking who owes what quickly becomes tedious, especially with fluctuating expenses. GoodShare automates this process: set up your income ratio once, log shared expenses as they occur, and the app continuously calculates each person's fair share. It tracks balances over time and shows who needs to compensate whom. The app supports multiple currencies and works offline, syncing whenever you're back online.