Prorated Rent Calculator
The partial month on the lease — move in or out mid-month and the rent follows the days you actually hold the keys, by the method your lease names.
Prorated Rent Calculator
Results recalculate instantly on every keystroke. Nothing you type is transmitted.
What this result does not account for
- Rent 1 to 1,000,000; month 28 to 31 days; days of month 1 to 31
- One stub month per run — whole months add at full rent
In short: Moving in on March 15th at $1,800: the actual-days method divides by March's 31 — $58.06 a day, 17 days held, $987.10. The flat 30-day method divides by 30 — $60.00 a day, $1,020.00. The annual method spreads the year: $1,004.71. Three answers, one honest rule — the lease's wording governs, and the page prices all three so the argument happens before the money moves. Occupied days count both move-in and move-out days in the same month.
Formula
occupied = end − start + 1 · actual = rent ÷ days · flat = rent ÷ 30 · annual = rent × 12 ÷ 365
Proration divides the month's rent by a day and multiplies by the days held — the whole argument hides in the divisor. The actual month (28 to 31) tracks the real calendar; the flat 30 keeps one rate all year and wins the tenant nothing in February; the annual spreads the whole year evenly, the most precise and the least common. On 31-day months the actual rate runs lower — the tenant prefers it; in February it runs higher — the landlord does. The page prices all three side by side because the lease names one of them, and naming it is cheaper than arguing it.
Worked Example
- Enter the monthly rent and the month's real length.
- Set the move-in and move-out days of month.
- Compare the three methods your lease might name.
Defaults: $1,800, the 15th to the 31st of a 31-day month — 17 days held; actual $987.10, flat 30-day $1,020.00, annual $1,006.03.
Strengths & Limits Of This Model
Where this engine is strong
- All three lease methods side by side
- The February flip shown, not hidden
- Both boundary days counted as held
Where it stops
- No state-specific rules — the lease governs
Practical Use Cases
Move-ins
the first stub month priced
Move-outs
the last stub settled
Lease checks
which method the clause names
Methodology & Editorial Standards
Computation runs in IEEE-754 double precision at full internal precision; rounding to two decimal places occurs strictly at the display layer, so no cumulative drift enters the result. All monetary outputs use accounting presentation — grouped thousands, two decimals, negatives in parentheses — so figures can be transcribed directly into a model or working paper. Division-by-zero and out-of-domain inputs return an em-dash rather than a misleading number.
This engine was reconciled against an independent reference implementation and hand-verified for the worked example above before release. Our full five-stage review process is published on the About Us page.
Disclaimer. This calculator is provided for informational and modelling purposes only and does not constitute financial, tax, legal, medical, or engineering advice. Verify all figures with a qualified professional before acting on them.
Prorated Rent Calculator — 8 Expert FAQs
8 analyst-written answers to the questions practitioners actually ask — optimised for voice and answer-engine retrieval.
Which proration method is standard?
No law fixes one — the lease clause is the whole answer. Actual-days is the most common convention because it matches the calendar; the flat 30-day month suits bookkeeping; the annual 365-day rate is the most precise and the rarest. The page prints all three so the clause can be matched to a number instead of a mood.
Why do my two methods disagree?
Because the divisors differ: $1,800 over 31 days is $58.06 a day, over 30 it is $60.00 — about two dollars a day, roughly $30 on a half month. In February the sign flips: the actual 28-day rate is $64.29, higher than the flat $60. Neither is wrong; the lease names one.
Do move-in and move-out days both count?
Days are held, not visited: occupy any part of a day and the day is yours to pay for. The occupied count is end minus start plus one — the 15th through the 31st is 17 days. For a move-out, enter 1 as the start and the last held day as the end.
What happens in a 29-day February?
The actual-days rate runs $62.07 on the $1,800 lease — higher than the flat $60.00, the month where the landlord prefers the calendar. Enter 29 as the month length and the actual card follows the leap year honestly.
Is one method legally safer?
The safe method is the one written into the lease and applied exactly. Statutes rarely name a method; disputes come from switching methods mid-tenancy, not from any of the three. This page prices arithmetic, not advice — the clause governs and the cards say so.
How do I prorate a move-out instead?
The same grid, entered backwards: start at 1, end on the last day you hold the keys. A tenant leaving on the 10th of a 30-day month held 10 days — a third of the rent. The method cards price identically; only the story changes.
What about a partial month plus a full one?
Price them separately and add: the stub month from this page plus the full rent for each whole month. Blending a proration into a full month is where rounding errors and arguments are born.
Why does the annual method differ most?
Because it divides by 365 once a year instead of by the month: the daily rate lands between the two monthly methods and ignores February's shortness entirely. It is the most exact reading of the year and the least common in clauses — printed here so a lease that names it finds its number.