Housing & Life

Roommate Budget Splitter

Stop arguing about the wifi bill. Here's the transparent formula — choose your split style.

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All calculations happen in your browser. Nothing leaves this page.

Monthly rent (USD)

Monthly utilities + internet

Monthly shared groceries / consumables

Split style

Roommate A — monthly income (USD)

Roommate B — monthly income (USD)

Roommate C — monthly income (USD)

Roommate A — room share (%)

Roommate B — room share (%)

Roommate C — room share (%)

Roommate A — custom weight (%)

Roommate B — custom weight (%)

Roommate C — custom weight (%)

Idle

How to use this calculator well

Pick a split style. Equal is rare — most groups use income-weighted or room-size-weighted.
For income-weighted, use monthly take-home (post-tax). It's the fairest signal of what each person can spare.
For room-weighted, write down each bedroom's square footage, then set the % to match.
Custom weights let you encode niche deals — e.g., the one with the private bathroom pays 5% more.
Utilities and shared groceries use the same weights. If the pattern is different (one wants only rent split, another wants all split), make two passes.

Frequently asked questions

What's the most common fair split?

Room-size-weighted is the most-cited model in flatmate research from the OECD. Income-weighted is the most-cited model in co-living philosophy. Both beat equal split on perceived fairness.

Should utilities be split by usage?

For flat-rate internet, yes. For metered utilities, consider usage tracking — Submetering isn't usually worth it for 3 roommates.

What if someone can't pay?

Set a 30-day grace policy up front. Have the others cover and carry the balance as a written IOU. Don't let resentment build.

Where this estimate falls short

Doesn't handle partial months or mid-month move-ins.
Doesn't model separate-room electricity if you have it.
If two of three work from home and one doesn't, consider a 'home presence' weight instead of pure income.

Roommate Budget Splitter

Try it

How to use this calculator well

Frequently asked questions

Where this estimate falls short

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