Fair Split Calculator
Split expenses fairly based on income instead of 50/50. Enter each person's earnings and the total amount to split. The calculator shows each person's proportional share — higher earners pay more, making expenses affordable for everyone. Free to use, privacy-preserving, works for any shared cost.
Split by Income
Higher earners pay more. Income is not stored.
Examples: monthly rent, utility bills, vacation costs
Common questions about fair splitting
Is 50/50 always fair for couples?
Not necessarily. When one partner earns $80k and the other earns $40k, equal splitting means the lower earner pays twice the percentage of their income. Income-based splitting equalizes the financial burden, making it fairer for both partners.
Should roommates split rent by income or equally?
It depends on your situation. If incomes are similar (within 20%), equal splits work fine. But when roommates have significantly different salaries, income-based splitting keeps rent affordable for everyone and prevents financial strain.
How do coparents calculate child expense splits fairly?
Courts often use proportional splitting based on income. If one parent earns $90k and the other earns $60k (60/40 split), child expenses like medical bills, tuition, and activities split the same way. This reflects actual earning capacity.
What's the difference between equal split and fair split?
Equal split means everyone pays the same dollar amount (50/50). Fair split (income-based) means everyone pays the same percentage of their income. Fair splitting accounts for income differences and makes shared costs more equitable.
Real-world splitting examples
Example 1: Splitting rent with roommates
Scenario: Three roommates, $2,400/month rent
- • Alex earns $90,000/year
- • Jordan earns $60,000/year
- • Taylor earns $50,000/year
- • Total income: $200,000/year
Fair split (income-based):
- • Alex pays 45% = $1,080/month
- • Jordan pays 30% = $720/month
- • Taylor pays 25% = $600/month
vs. Equal split: $800 each (much harder for Taylor)
Example 2: Couples splitting utilities and groceries
Scenario: Partners with different incomes, $500/month shared bills
- • Partner A earns $75,000/year
- • Partner B earns $45,000/year (grad student)
- • Total income: $120,000/year
Fair split (income-based):
- • Partner A pays 62.5% = $312.50/month
- • Partner B pays 37.5% = $187.50/month
This keeps expenses affordable during grad school years.
Example 3: Coparents splitting child expenses
Scenario: Shared child expenses, $1,200/month (daycare, activities, medical)
- • Parent A earns $100,000/year
- • Parent B earns $50,000/year
- • Total income: $150,000/year
Fair split (income-based):
- • Parent A pays 67% = $800/month
- • Parent B pays 33% = $400/month
Courts often mandate this proportional approach for shared child costs.
Example 4: Friends splitting vacation costs
Scenario: Weekend trip, $1,800 total (hotel, rental car, shared meals)
- • Friend A earns $120,000/year
- • Friend B earns $70,000/year
- • Friend C earns $50,000/year (teacher)
- • Total income: $240,000/year
Fair split (income-based):
- • Friend A pays 50% = $900
- • Friend B pays 29% = $525
- • Friend C pays 21% = $375
Everyone enjoys the trip without financial stress.
When to use income-based splitting
Roommates with different salaries
Equal rent feels unfair when one person earns $45k and another earns $90k. Split by income keeps housing affordable.
Couples keeping finances separate
Split shared bills proportionally instead of 50/50. Especially helpful when one partner is in grad school or between jobs.
Coparents with different incomes
Child expenses split proportionally reflect actual earning capacity. Courts often mandate this approach.
Friend groups with income gaps
Trips and dinners stay accessible when higher earners contribute more. Everyone enjoys without financial stress.
How the calculation works
Income-based splitting calculates each person's share as a percentage of total group income.
Example:
• Person A earns $90,000/year
• Person B earns $60,000/year
• Total rent: $2,000/month
Calculation:
• Total income: $150,000
• Person A: ($90k / $150k) × $2,000 = $1,200
• Person B: ($60k / $150k) × $2,000 = $800
Person A pays 60%, Person B pays 40%. Fair for both.
Why fairness matters
Equal splits seem fair on the surface — everyone pays the same amount.
But equal isn't always equitable. Someone earning $45k paying $1,000/month in rent sacrifices 27% of their gross income. Someone earning $90k paying the same sacrifices 13%.
Income-based splitting equalizes the burden instead of the amount. Both people sacrifice the same percentage of their earnings.
Equal split vs fair split: Which is better?
Choosing between equal (50/50) and fair (income-based) splitting depends on your situation. Here's how they compare:
| Factor | Equal Split (50/50) | Fair Split (Income-Based) |
|---|---|---|
| Best for | Similar incomes (within 20%) | Different income levels |
| Financial burden | Unequal % of income | Equal % of income |
| Transparency | Simple, easy to understand | Clear with calculator |
| Typical use cases | Friends, short-term roommates | Couples, coparents, long-term roommates |
| Affordability | Can strain lower earners | Sustainable for everyone |
| Court acceptance | Rarely mandated | Often required for child expenses |
Pro tip: Start with the calculator to see what both approaches look like for your situation. The numbers often make the decision clear.
Beyond the calculator
This calculator works for one-time calculations. For ongoing expense tracking with automatic income-based splits:
Set income percentages once
Every future expense splits automatically.
Track running balances
See who owes what in real-time.
Complete history
Never lose records. Export anytime.
14-day free trial • No credit card required
Related Resources
Frequently Asked Questions
- How does income-based splitting work?
- Instead of splitting 50/50, expenses are divided proportionally based on income. Someone earning $90k and someone earning $60k would split 60/40. This makes shared expenses more affordable for lower earners.
- When should I use income-based splitting?
- Use it when incomes vary significantly in your group — roommates, couples, coparents. It's especially helpful for ongoing expenses like rent, utilities, or child costs where equal splits might strain lower earners.
- Is my income data stored?
- No. This calculator runs in your browser only. Nothing is saved or sent to servers unless you request an email copy. Are We Even's full app also doesn't store income data — only split percentages.
- Can I use this for more than 2 people?
- Yes. Add up to 5 people. The calculator works the same way — everyone's share is proportional to their income as a percentage of total group income.
- What if someone has no income?
- Enter $1 as their income. They'll pay a minimal share. Or exclude them entirely and split among earners only.