How to read this result
In the default example, person 1 share is $1,200.00. This model splits rent among three people. Use the same units for every weight: room area, custom allocation points or income.
Change one assumption at a time to see how it affects the scenario. Compare periods and cost definitions consistently. Negative results show a modeled shortfall; an unavailable ratio needs a valid denominator.
Formula and methodology
Split the entered total rent among three people. Equal mode assigns one third each. The other modes normalize the three user-entered room-size, allocation-point or income weights.
Enter percentages as whole numbers: 5 means 5%. When used as a factor, the calculation divides a percentage by 100. Percentage outputs multiply the final ratio by 100. Calculations retain precision internally; displayed amounts and rates are rounded to two decimals.
Variables and input definitions
- Total monthly rent (USD/month)
- Total rent to allocate. Minimum: 0.
- Split mode (select)
- Equal, bedroom size, custom weights or income-weighted.
- Person 1 weight / room size (weight)
- Default uses room square footage. Minimum: 0.
- Person 2 weight / room size (weight)
- Default uses room square footage. Minimum: 0.
- Person 3 weight / room size (weight)
- Default uses room square footage. Minimum: 0.
Worked example
This example uses the exact prefilled inputs above. Reset defaults to restore this scenario after making changes.
| Item | Default scenario |
|---|---|
| Total monthly rent | $3,000.00 |
| Split mode | Bedroom size |
| Person 1 weight / room size | 180 |
| Person 2 weight / room size | 150 |
| Person 3 weight / room size | 120 |
| Item | Default scenario |
|---|---|
| Person 1 share | $1,200.00 |
| Person 2 share | $1,000.00 |
| Person 3 share | $800.00 |
Assumptions and limitations
Allocation method is a household agreement tool, not a legal determination of responsibility under a lease.
This model splits rent among three people. Use the same units for every weight: room area, custom allocation points or income.
The tool uses values you supply. It does not retrieve market prices, verify leases or inspect a property. Results exclude items outside the listed inputs. Review local requirements and the relevant contract when a payment, fee or allocation depends on them.
Common mistakes
Use a consistent unit across all three weights. Room size alone does not account for bathrooms, common spaces or amenities unless the group explicitly agrees on that convention.
Sources and method references
These references provide context for the method and terminology. They do not endorse this tool or validate your property assumptions.
- GovInfo / HUD — 24 CFR §880.608 — Security deposits (federal housing program example)Program-specific example referencing state/local deposit requirements; not a national interest-rate rule.
Frequently asked questions
Does the calculator decide what is fair?
No. It applies the selected allocation rule. Roommates should agree on the weights and what shared space or amenities contribute to them.
What happens with a zero weight?
That person receives zero rent allocation in a weighted mode. All three weights cannot be zero; equal mode does not use the weights.