How to read this result
In the default example, chargeable days is 15. Results describe this input scenario; they are not a recommendation.
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
Chargeable days run from the selected start day through the end of the entered month, with the start day included only when selected. Divide monthly rent by actual month length or an explicit 30-day denominator, then multiply by chargeable days.
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
- Monthly rent (USD/month)
- Full monthly rent. Minimum: 0.
- Move-in / start day (day of month)
- First chargeable day, inclusive by default. Minimum: 1. Maximum: 31.
- Days in month (days)
- Actual calendar days for selected month. Minimum: 28. Maximum: 31.
- Method (select)
- Actual-days default; optional 30-day convention clearly labeled.
- Include start day (boolean)
- Default inclusive.
Worked example
This example uses the exact prefilled inputs above. Reset defaults to restore this scenario after making changes.
| Item | Default scenario |
|---|---|
| Monthly rent | $2,400.00 |
| Move-in / start day | 16 |
| Days in month | 30 |
| Method | Actual days |
| Include start day | Yes |
| Item | Default scenario |
|---|---|
| Chargeable days | 15 |
| Daily rent | $80.00 |
| Prorated rent | $1,200.00 |
Assumptions and limitations
Lease terms and state/local law may specify a different proration convention; calculator does not determine legal entitlement.
Results describe this input scenario; they are not a recommendation.
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
The 30-day option changes the daily-rate denominator. It does not change the actual date range. Use the convention in the lease or applicable agreement.
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
Is the move-in day charged?
The include-start-day checkbox controls that choice. For day 16 of a 30-day month, including the day charges 15 days; excluding it charges 14.
Can I enter day 31 in a 30-day month?
No. The calculator validates the start day against the selected month length.