Rent increase split calculator
Your rent went up. Compare each roommate's old and new share under three clear rules before anyone commits.
Enter each person's current share — they should add up to the current total.
How it works
Keep current percentages — each person's current share is used as a weight against the new total, preserving the existing proportions exactly.
Split only the increase equally — the raise is divided evenly and added on top of each existing share. Everyone absorbs the same dollar increase regardless of their current share.
Use new percentages — you set a fresh percentage split that must total 100%, applied to the new total. Use this to renegotiate the agreement when rent changes.
Worked example: Old rent $1,500 split $900 / $600. New rent $1,650 (+$150). Keep ratio: 1,650 × 900 ÷ 1,500 = $990 and $660. Split increase equally: $900 + $75 = $975 and $675. New 50/50: $825 each.
Money is held in cents and distributed with the largest-remainder rule, so the new shares always add back to the new total.
FAQ
- Which rule is fairest?
- There is no single fair rule — it depends on your existing agreement. Keeping percentages preserves the original deal; splitting the increase equally treats the raise as a shared burden; new percentages let you renegotiate. The calculator shows all three so you can compare.
- My current shares aren't equal. Is that OK?
- Yes. Enter whatever each person currently pays. The keep-ratio and equal-increase methods both start from your real current shares rather than assuming an even split.
- Does this say whether the rent increase is legal?
- No. RoomRatio only redistributes an amount you enter. Statutory caps, rent-control limits, and notice rules are outside this tool — check your local rules.
- Can I handle a rent decrease?
- Not yet. The calculator currently requires the new rent to be the same as or higher than the current rent.