Free prorated rent calculator
Find the rent you owe for a partial month in two seconds. Enter the monthly rent, the days you occupy the unit, and the days in the month — then pick the actual-days, 30-day, or 365-day method. The calculator returns the prorated rent and the daily rate it is built from — updated live, as you type.
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Estimates only, based on the values you enter. Not legal advice.
Results are estimates. Consult a professional.
What is prorated rent?
Prorated rent is the portion of a month's rent that covers only the days a tenant actually occupies the property. When someone moves in halfway through the month — or moves out before it ends — charging a full month would mean paying for days they never had access to the unit. Proration splits the month fairly: the tenant pays a daily rate for each day they hold the keys, and nothing for the days they don't. It is the number this prorated rent calculator returns the moment you enter the monthly rent and the days occupied.
The most common reason to prorate is a mid-month move-in. A landlord prorates the first partial month so that, from then on, rent is collected cleanly on the 1st of every month. The same logic applies on the way out: a tenant leaving on the 10th may only owe for those 10 days. Proration is standard practice for landlords and property managers — and in a few states, such as California, it is required by law.
How to calculate prorated rent
Calculating prorated rent is a three-step process. First find the daily rent, then count the days the tenant occupies the unit, then multiply. The calculator above does all three live, but here is the logic by hand.
- Find the daily rate. Divide the full monthly rent by the number of days in that month. For $1,200 rent in a 30-day month, that is $1,200 ÷ 30 = $40 per day.
- Count the days occupied. For a move-in, count from the move-in date through the last day of the month, including the move-in day itself. For a move-out, count from the 1st through the move-out day.
- Multiply. Daily rate × days occupied = prorated rent. At $40 a day for 16 days, the tenant owes $640 for the partial month.
Prorating methods compared
There is no single legally mandated formula in most of the US, so three conventions are in common use. They agree closely but not exactly, because each divides the monthly rent by a different number of days. The calculator lets you switch between all three.
| Method | Daily rate formula | Best for |
|---|---|---|
| Actual days in month | monthly rent ÷ days in that month (28–31) | The fairest, most common method; assumed by most state laws |
| 30-day (banker's month) | monthly rent ÷ 30 | Simplicity; the exclusive method in some states (e.g. California) |
| 365-day (annual) method | (monthly rent × 12) ÷ 365 | Commercial leases and year-long agreements |
All three multiply the daily rate by the days occupied; only the denominator differs.
Why the methods disagree: a 31-day month gives a lower daily rate under the actual-days method than under the 30-day method, because the rent is spread over more days. February — with only 28 or 29 days — flips that: the actual-days daily rate is the highest of the three. Over a full month the totals all return to one month's rent, but for a partial month the choice of method changes the bill by a few dollars. The lease should state which method applies.
A worked example using the prorated rent calculator
Dana signs a lease at $650 a month and picks up the keys on September 15th. September has 30 days. Here is exactly how the calculator arrives at what Dana owes for that first partial month.
Step 1 — Find the daily rate
Using the actual-days method, divide the $650 monthly rent by the 30 days in September: $650 ÷ 30 = $21.67 per day.
Step 2 — Count the days occupied
Dana occupies the unit from the 15th through the 30th. Counting inclusively, that is 30 − 15 + 1 = 16 days.
Step 3 — Multiply
Switch the calculator to the 30-day method and the daily rate becomes $650 ÷ 30 = $21.67 as well (September already has 30 days, so the two agree here). Try the same move-in date in a 31-day month and you will see the methods diverge by a few dollars — which is exactly why the lease should name the method.
When prorated rent applies: move-in and move-out
Moving in mid-month
This is the most common case. A tenant whose lease starts on the 20th shouldn't pay a full month for 11 days of occupancy. Landlords typically prorate this first month so that every subsequent payment lands on the 1st — it keeps the rent roll clean and the tenant only pays for what they use.
Moving out mid-month
When a lease ends or a tenant gives notice for a date partway through the month, the final month can be prorated to the move-out day. This is less automatic than a move-in: in many states a landlord is not obliged to prorate the last month unless the lease says so, so it is often a point to negotiate and to get in writing.
- First month of a new lease — the standard, near-universal use of proration.
- Final month on move-out — common, but check the lease; not always required.
- Lease changes mid-month — a rent increase or a roommate change that takes effect partway through the month.
- Short-term and corporate stays — where occupancy rarely lines up with calendar months.
Is prorated rent required by law?
In most of the United States, no federal or statewide law requires a landlord to prorate rent — it is a widespread courtesy and business practice rather than a universal right. Whether you are owed prorated rent usually comes down to your lease and your local landlord-tenant law.
A handful of states do mandate it. California, for example, requires landlords to prorate rent for partial-month occupancy and specifies the daily-rate (actual-days) method. Other jurisdictions are silent, leaving it to the lease. Because the rules vary so much by state and city, the safest move is the same one experts repeat everywhere: get the proration agreement in writing before you move in or out.
Tips for landlords and tenants
- Name the method in the lease. State whether proration uses actual days, a 30-day month, or the 365-day method so there is no dispute later.
- Agree before you sign or give notice. Especially for move-out proration, which many landlords aren't required to offer — put it in writing.
- Count the move-in day. The day the keys change hands is an occupied day; leaving it out short-changes the landlord by a day's rent.
- Keep the deposit separate. Prorated rent is rent for partial occupancy; it is not your security deposit and shouldn't be confused with it.
Working out a budget around a move? Pair this with a rent affordability calculator to size your target rent, then a monthly budget to fit it in.
Sources and methodology
The three proration methods, formulas, and the worked example above follow the conventions used across major rental and property-management resources, including Omni Calculator, Zillow, and landlord-management guides. The legal note reflects that proration is generally a lease matter except where state law (such as California Civil Code) requires it.
Omni Calculator — Prorated Rent Calculator (definition, formula, and worked example).Zillow Rentals — Prorated Rent Calculator and guide.Frequently asked questions about the free prorated rent calculator
About this prorated rent calculator
This prorated rent calculator runs entirely in your browser. Every figure you enter stays on your device — nothing is sent to a server, logged, or shared. It divides the monthly rent into a daily rate using the method you pick (actual days in the month, a 30-day banker's month, or the 365-day annual method) and multiplies by the days occupied, updating instantly as you type.
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