Fair Expense Splitting in Shared Apartments: 3 Strategies

Living with roommates is great for your wallet but can be terrible for friendships. The number one reason? Money disagreements. Who pays for what, who owes whom, and the eternal question: "Is this really fair?"

There's no universally "correct" way to split expenses. What works depends on your specific situation: income levels, room sizes, lifestyle differences. Here are three strategies, when to use each, and how to implement them without losing friends.

Strategy 1: The Equal Split (50/50 or 33/33/33)

The simplest approach: divide everything equally by the number of roommates. Rent is 1,200 EUR, three people, each pays 400 EUR. Same for utilities, internet, and shared groceries.

When it works

• Everyone has similar income levels
• Rooms are roughly the same size and quality
• Lifestyles are similar (all home a lot, or all rarely home)
• You value simplicity over perfect fairness

When it fails

• One person has the master bedroom with ensuite, another has a tiny room
• Significant income disparity (student living with professionals)
• One person works from home (uses more utilities)
• Different eating habits (vegan vs. meat eater sharing groceries)

How to implement

Simple math: Total / Number of people = Each person's share.

Pro tip: Create one shared expense for fixed monthly costs (rent + utilities + internet = one number). This reduces the number of transactions and arguments.

Strategy 2: Income-Based Split

Each person pays proportionally to their income. If you earn more, you pay more. This feels fair when there's a big income gap.

The formula

Your share = (Your income / Total income) x Total expenses

Real example

Three roommates with monthly net income:

• Anna: 3,000 EUR
• Ben: 2,000 EUR
• Chris: 1,000 EUR (student)

Total income: 6,000 EUR
Shared expenses: 1,500 EUR/month

Anna pays: (3,000 / 6,000) x 1,500 = 750 EUR (50%)
Ben pays: (2,000 / 6,000) x 1,500 = 500 EUR (33%)
Chris pays: (1,000 / 6,000) x 1,500 = 250 EUR (17%)

When it works

• Big income differences (mixing students with professionals)
• Everyone agrees that "fair" means proportional to ability to pay
• You're comfortable sharing income information

When it fails

• The higher earner has the smallest room (double unfair)
• Income changes frequently (freelancers, commission-based jobs)
• Someone feels uncomfortable sharing their income
• Resentment builds: "I pay more but use the same amount"

How to implement

Agree on a percentage split at move-in based on current incomes. Review quarterly or when someone's income significantly changes. Use net income (after taxes) for a more accurate picture of what people can actually afford.

Strategy 3: Usage-Based Split

The most precise but most complex approach: you pay for what you use. Bigger room? Pay more rent. Work from home? Pay more utilities. Eat more groceries? Pay for them.

How to calculate room-based rent

Split rent based on room size (square meters).

Your rent = (Your room sqm / Total bedroom sqm) x Total rent

Real example

Apartment: 90 sqm total, 1,200 EUR rent
Bedrooms: 20 sqm + 15 sqm + 10 sqm = 45 sqm of bedrooms

Room A (20 sqm): (20/45) x 1,200 = 533 EUR
Room B (15 sqm): (15/45) x 1,200 = 400 EUR
Room C (10 sqm): (10/45) x 1,200 = 267 EUR

Optional: Factor in room quality

Not all square meters are equal. Consider adding modifiers:

• Ensuite bathroom: +10-15%
• Balcony access: +5-10%
• Street noise / no natural light: -10%
• Walk-through room (no privacy): -15%

Splitting utilities by usage

This is where it gets complex. Options:

• Estimate days at home: If Ben works from home 5 days/week while others work in offices, Ben uses more electricity and heating
• Track actual usage: Smart plugs, separate meters (usually not worth the effort)
• Hybrid approach: Base utilities (heating, water) split equally; electricity by estimate

When it works

• Very different room sizes or quality
• Very different lifestyles (one person travels constantly)
• Everyone values precision over simplicity
• You have the tools to track it easily

When it fails

• It becomes a source of constant debate ("I didn't eat that cheese!")
• Someone always feels cheated
• The overhead of tracking exceeds the benefit

Which Strategy Should You Choose?

Here's a quick decision guide:

Situation	Recommended Strategy
Similar rooms, similar income, similar lifestyle	Equal Split
Big income gap, similar rooms	Income-Based
Different room sizes, similar income	Usage-Based (for rent)
Different everything	Hybrid: Rent by room size, other expenses equal or income-based

Making It Work: Practical Tips

1. Agree before moving in

The worst time to discuss money is after resentment has built up. Set expectations on day one (or before).

2. Put it in writing

Not a legal contract, just a shared document everyone agrees to. "Rent: Room A pays X, Room B pays Y. Groceries: Split by whoever cooks."

3. Review regularly

Life changes. Jobs change. Do a check-in every 6 months: "Is this still working for everyone?"

4. Use a shared tracking tool

Spreadsheets get messy. Venmo requests feel transactional. Apps like GoodShare let everyone log expenses and see who owes whom without awkward conversations.

5. Separate personal from shared

Be clear about what's shared (toilet paper, dish soap) and what's personal (your special shampoo). Most arguments come from gray areas.

The Bottom Line

There's no perfect system. What matters is that everyone agrees it's fair and commits to following it. The best approach is the one your specific group can stick to.

Start simple. If equal doesn't feel right, try income-based. If rooms are very different, factor that in. Adjust as you go.

"Fairness isn't about perfect math. It's about everyone feeling respected."