How to Calculate Prorated Rent: Three Methods, Worked Examples, and Which One to Use

July 5, 2026

A tenant moves in on the 19th. What do they owe for the rest of the month? The answer depends entirely on which proration method you use — and if your lease doesn't name one, you're negotiating math with a stranger during move-in week. Here's how each method works, where they diverge, and how to lock your choice in before it matters.

When proration applies

Proration comes up in four situations: a mid-month move-in, a mid-month move-out (where the lease allows it), a rent change that takes effect mid-cycle, and the first partial month after a lease renewal shifts the due date. In every case the question is the same: what is one day of rent worth?

Almost no state law dictates a proration method for private leases. It's a contract term — which means the method in your lease controls, and a lease that's silent invites a dispute over a number you could have fixed in one sentence.

Method 1: Actual days in the month

Divide the monthly rent by the number of days in that specific month, then multiply by the days the tenant occupies the unit.

Example: Rent is $1,500. The tenant moves in on the 19th of a 31-day month, occupying 13 days (the 19th through the 31st, counting move-in day).

$1,500 ÷ 31 = $48.39 per day. $48.39 × 13 = $629.03.

This is the most common method and the easiest to defend: the daily rate reflects the actual month. The quirk is that a day of rent is cheaper in July than in February — the same tenant moving in on the 19th of a 28-day February would owe $535.71 for 10 days at $53.57 each.

Method 2: The banker's month (30-day method)

Divide the monthly rent by a flat 30, regardless of the calendar.

Example: $1,500 ÷ 30 = $50.00 per day. Thirteen days = $650.00.

The appeal is consistency — every month prices the same — and round numbers. The cost is small distortions in 31-day months (the tenant slightly overpays per day) and February (they underpay). Some property managers prefer it precisely because the daily rate never changes; just apply it in both directions, move-in and move-out, or the inconsistency will look self-serving.

Method 3: Days in the year (365-day method)

Multiply the monthly rent by 12, divide by 365, and use that as the daily rate.

Example: $1,500 × 12 = $18,000. $18,000 ÷ 365 = $49.32 per day. Thirteen days = $641.10.

This produces the most "honest" daily rate across a full year and shows up in some commercial leases, but it's rare in residential practice and harder to explain to a tenant at the kitchen table. Leap years add a wrinkle — a lease using this method should say whether the divisor is 365 or 366.

Which method should you use?

For most self-managing landlords: actual days in the month. It's intuitive, tenants can verify it on a phone calculator, and no method survives a dispute better than "the rent divided by the days in this month." Whichever you pick, two rules keep it clean:

• Name the method in the lease. One sentence: "Prorated rent is calculated using the actual number of days in the applicable month." That sentence ends every future argument.
• Apply it symmetrically. The same method for move-ins and move-outs, for every tenant, every time. Switching methods to whichever favors you in the moment is the kind of pattern that reads badly in front of a judge.

One more convention worth writing down: whether move-in day itself is a paid day (it should be — the tenant has possession) and whether you prorate the first month or the second. Many landlords collect a full first month plus deposit at signing and prorate the second month instead, which simplifies move-in funds when the prorated amount is small.

Skip the arithmetic

Our free prorated rent calculator runs all three methods side by side from your rent, move-in date, and month — so you can see exactly how much the choice changes the number before you commit it to the lease.

And if you'd rather never do this by hand again: StackRent calculates prorated amounts automatically when a lease starts or ends mid-month and posts them straight to the tenant ledger. Join the waitlist for early access.

This article is for informational purposes and isn't legal advice. Lease requirements vary by state — verify current rules for your jurisdiction, starting with our state guides.