Split Rent Calculator

"Fairest" depends on what fairness means to your group. An equal split is simplest and preserves a sense of parity. A space-based split rewards roommates in smaller rooms. An income-based split ensures everyone can afford their share. The method that works best is the one all roommates agree to in advance and feel comfortable with; there is no universally correct answer.

Measure each bedroom in square feet and calculate each roommate's share as their room size divided by the total of all bedrooms. Apply that percentage to the rent. For example: rooms of 200, 150, and 100 sq ft total 450 sq ft. The roommate in the 200 sq ft room pays 44%, the 150 sq ft room pays 33%, and the 100 sq ft room pays 22%. Common areas are shared equally. This calculator's "Room Sizes" toggle handles this automatically.

Most roommates split utilities equally for simplicity. However, if usage is clearly unequal (one person works from home and uses significantly more electricity and internet bandwidth, or one person showers twice daily) a usage-adjusted split may feel fairer. Smart home devices or sub-metering can measure actual usage in some setups. Otherwise, adjusting by agreed percentages (e.g., the WFH roommate pays 10–15% more of the utility bills) is a practical middle ground.

A partner who stays regularly (more than a few days a week) adds meaningful utility and supply usage: water, electricity, food, and shared space consumption. A common fair adjustment is to add 10–20% to that roommate's utility share, or to collect a small flat contribution from the couple. This should be discussed openly and agreed upon before it becomes a point of tension. Enable the "Has a partner" option in this calculator to factor this in.

Splitting shared costs based on income is entirely legal and entirely informal; it is a private agreement between roommates. The landlord is typically only concerned with the total rent being paid on time, not how roommates divide it. Income-based splitting is common in long-term co-living arrangements among friends, couples, and intentional communities. It has no legal status on its own and relies entirely on mutual agreement and trust.

A roommate who is away frequently uses fewer shared resources: water, electricity, and space consume less when someone is not there. Some groups adjust utility splits to reflect this. A modest reduction of 10–15% from variable utility costs for a frequent traveler is reasonable. Rent, however, is typically held constant regardless of presence; the room is still occupied and unavailable, so the full rent contribution stays the same.

A private bathroom is a clear amenity advantage over a shared bathroom. Typical adjustments range from $50–$150 extra per month in most markets, reflecting the additional privacy and convenience. The exact premium depends on the apartment's location and the total rent amount. Enable the "Private Bathrooms" toggle in this calculator to have it automatically weighted into that roommate's share.

Apps like Splitwise, Venmo, and Zelle are popular for tracking and settling shared household expenses. For monthly rent splits, many roommates use a simple shared spreadsheet. The most important thing is not which tool you use but that all parties can see the calculations, agree to the amounts, and pay consistently. Transparency prevents disputes. Document the split method, individual amounts, and any adjustments at the start of the lease.