Prorated rent calculator: move-in, move-out and three methods compared

Prorated rent is the rent you owe for a partial month when you move in or out on a day other than the day rent is due. This prorated rent calculator works it out three ways at once (actual days in the month, a 30-day month, and a 365-day year), handles move-in and move-out, any rent due day, and periods that spill into the next month. Enter your numbers and the result updates as you type.

How to use the calculator

Enter the monthly rent and the day rent is due (usually the 1st). Choose moving in or moving out, then the date. Pick the method your lease names; if it is silent, leave it on actual days, the method HUD's model lease instructions use. For a move-in, add the deposit and any one-off charges to see the total due on the day. The breakdown box is written so you can paste it into an email to your landlord or tenant.

How prorated rent is calculated: the three methods

All three methods start the same way: find a daily rate, count the days, multiply. They differ only in what they divide the monthly rent by, and that is why two people with the same lease and the same dates can get different numbers.

Method	Daily rate	Who uses it	Effect
Actual days in the month	Monthly rent ÷ days in that month (28, 29, 30 or 31)	HUD model lease instructions; most private leases that specify a method	Fair across months; a day in February costs more than a day in March
30-day month (banker's month)	Monthly rent ÷ 30	Some public agencies and property managers; Caltrans rent proration examples	Same daily rate all year; slightly overcharges in 31-day months, undercharges in February
365-day year	Monthly rent × 12 ÷ 365	Some larger landlords and commercial leases	Lowest daily rate in most months; ignores leap years

Two official documents show both main methods in use. The U.S. Department of Housing and Urban Development's model lease instructions (Handbook 4350.3, Appendix 4-E) tell owners to divide the tenant's rent "by the actual number of days in the month" and multiply by the days the tenant will occupy the unit in the first rental period. The California Department of Transportation's rent proration examples (form 11-EX-5) use a 30-day month for every month, count both the start and vacate dates as days owed, and cap the prorated amount at one month's rent. This calculator follows the same counting rules: both ends of the period count, and the 30-day and 365-day results are capped at a full month.

The period itself is the part most online calculators get wrong when rent is not due on the 1st. For a move-in, you owe from the move-in date through the day before the next due date. For a move-out, you owe from the last due date on or before the move-out date through the move-out date. If that period crosses a month boundary under the actual-days method, each month is priced at its own daily rate, which is why the tool shows the split.

A worked example with the arithmetic

Example figures: rent is $1,650 a month, due on the 1st, and you move in on December 12. December has 31 days, so you are charged December 12 to 31, which is 20 days with both ends counted.

• Actual days: $1,650 ÷ 31 = $53.2258 per day. × 20 days = $1,064.52.
• 30-day month: $1,650 ÷ 30 = $55.0000 per day. × 20 days = $1,100.00.
• 365-day year: $1,650 × 12 ÷ 365 = $54.2466 per day. × 20 days = $1,084.93.

The spread between the highest and lowest method is $35.48 on one move-in. Now flip it to a move-out on February 10 in a non-leap year with rent of $2,000 due on the 1st: ten days charged. Actual days gives $2,000 ÷ 28 × 10 = $714.29; the 30-day method gives $666.67; the 365-day method gives $657.53. The order reverses, because February is short. That is the whole reason to check which method your lease names before you argue about the amount.

What a fair prorated rent looks like, and what to do next

A fair arrangement has four features: the lease names the method, both parties use the same due day, the move date on the paperwork matches the day keys change hands, and the figure is in writing before money moves. If the landlord's number is higher than the tool's actual-days result by more than a few dollars, ask which method they used. Most differences are a 30-day method applied to a 31-day month, or a period counted from the wrong due date.

If you are moving out, prorated rent is only one of the numbers in play. Rent increases that arrive with a renewal offer are covered by our rent increase calculator, which also lists state caps. Subscriptions and memberships you cancel mid-cycle work on the same logic, and the prorated refund calculator handles those. If a landlord refuses to prorate when the lease says they should, put it in writing using the structure in how to write a complaint letter that gets a reply. And if the move itself is the problem, the moving house checklist is the eight-week plan.

One legal note, stated plainly: there is no federal rule that requires a private landlord to prorate rent, and state rules vary. The lease governs. Where the lease is silent, proration is a negotiation, and the actual-days method is the easiest one to defend because it is the one a federal agency prints in its own lease instructions.

FAQ

How do you calculate prorated rent?

Divide the monthly rent by the number of days in the month to get a daily rate, then multiply by the number of days you occupy the unit in that partial month, counting both the first and last day. For $1,500 rent and a move-in on the 20th of a 30-day month, that is $50 a day times 11 days, or $550. Some leases divide by 30 or use a 365-day year instead.

Is prorated rent based on 30 or 31 days?

It depends on the method in your lease. The actual-days method uses the real length of the month, so 31 in December and 28 or 29 in February. The 30-day method treats every month as 30 days. HUD's model lease instructions use actual days; some agencies such as Caltrans use a 30-day month. If the lease does not say, actual days is the usual default.

Do landlords have to prorate rent?

No federal law requires a private landlord to prorate, and most states leave it to the lease. If your lease says rent is prorated for partial months, the landlord must follow it. If the lease is silent, proration is something to agree in writing before you sign. Many landlords prorate anyway because it fills a vacancy sooner.

How is prorated rent calculated for a move-out?

Count from the last rent due date on or before your move-out date through the move-out date itself, then multiply by the daily rate. If you paid a full month in advance, the refund is the full month minus the prorated amount. Give notice in the form your lease requires, because notice periods can change the date you stop owing rent.

What if rent is due on the 15th instead of the 1st?

The period shifts with the due date. Moving in on November 20 with rent due on the 15th means you owe November 20 through December 14. Under the actual-days method the November days are priced at the November rate and the December days at the December rate, which is why this calculator lets you set the due day and shows the split.

Does prorated rent include the security deposit?

No. The deposit is a separate amount held against damage or unpaid rent and is not reduced for a partial month. On move-in day you typically pay the prorated rent plus the full deposit plus any one-off charges. The calculator adds them for you when you enter the deposit and charges in the move-in fields.