You're signing a lease, the landlord slides over the move-in cost sheet, and there it is—a prorated rent amount that you're not quite sure how to verify. Is that number right? Should you just trust it?

This prorated rent calculator takes the guesswork out. Enter your monthly rent and move date, and you'll see exactly what you should owe for a partial month. Whether you're moving in on the 15th or vacating before your lease ends, you'll know the correct amount before you write that check.

The math itself isn't complicated, but the details matter—like whether your landlord divides by 30 days or the actual days in the month. We'll break down both approaches so you can double-check any number that comes your way.

Prorated rent is simply paying for only the days you actually live somewhere. Instead of forking over a full month's rent when you're only there for 12 days, you pay proportionally for those 12 days.

This comes up in two situations:

Move-in proration: Your lease starts mid-month. Rather than cooling your heels until the 1st, you grab the keys on the 18th and pay only for those remaining days of the month.

Move-out proration: Your lease wraps up before the month does, or you give notice and leave early. You pay through your last day, not the full month.

Most landlords are happy to prorate for move-ins—it gets you in faster and gets them paid sooner. Move-out proration is more hit-or-miss and often depends on what your lease says.

Here's the formula:

(Monthly Rent ÷ Days in Month) × Days Occupied = Prorated Rent

Breaking that down:

• Monthly rent: What you normally pay for a full month
• Days in month: The actual calendar days in that specific month (28, 29, 30, or 31)
• Days occupied: How many days you'll actually be living there

For move-ins, count from your first day through month's end. For move-outs, count from the 1st through your last day.

Quick example: $1,500 rent, moving in March 15th.

• March has 31 days
• You'll be there 17 days (15th through 31st)
• $1,500 ÷ 31 × 17 = $822.58

That's it. No hidden fees, no complicated adjustments—just simple division and multiplication.

1. Enter your monthly rent in the first field.
2. Select move-in or move-out depending on your situation.
3. Pick your month from the dropdown. The calculator already knows February has 28 days and July has 31—you don't need to remember.
4. Enter your move day. For move-ins, that's your first day in the unit. For move-outs, it's your last.
5. Check your result. Screenshot it or write it down before your landlord meeting.

Here's a scenario that happens all the time.

The situation: Sarah found an apartment in Chicago. Rent is $1,800/month, and she's getting keys September 20th. She knows about prorated rent but isn't sure what her total move-in cost will be.

The prorated calculation:

• Monthly rent: $1,800
• September has 30 days
• She'll occupy 11 days (September 20–30)
• $1,800 ÷ 30 × 11 = $660.00

But here's what catches people off guard: Most landlords collect the prorated amount PLUS next month's rent at move-in. So Sarah's actual move-in payment looks like this:

That's a big number to see for the first time at lease signing. Running these calculations beforehand means no sticker shock—and no awkward "Can I Venmo you the rest next week?" conversations.

Now the flip side.

The situation: Marcus is ending his lease in Dallas. His rent is $1,400/month, and his last day in the apartment is July 18th. He wants to make sure he's not overpaying.

The calculation:

• Monthly rent: $1,400
• July has 31 days
• He's there 18 days (July 1–18)
• $1,400 ÷ 31 × 18 = $812.90

Instead of $1,400, Marcus owes $812.90. That's $587 back in his pocket—worth the two minutes it takes to calculate.

Pro tip: If your landlord already collected July's full rent and you're leaving mid-month, you should get a refund for those unused days. Don't assume they'll calculate it automatically. Send an email with your move-out date and the prorated amount you expect back. Paper trails prevent "misunderstandings."

This is where most landlord-tenant math disagreements start.

Method 1: Actual days (more accurate)

Divide by the real number of days in that month:

• January, March, May, July, August, October, December → 31 days
• April, June, September, November → 30 days
• February → 28 days (29 in leap years)

Method 2: Flat 30-day (simpler, less precise)

Always divide by 30, no matter the month.

Does the difference matter? Let's check. For $1,500 rent, staying 10 days in January:

Sixteen bucks isn't going to break the bank, but it adds up if you're in a higher-rent apartment or staying longer. More importantly, understanding this explains why your calculation and your landlord's might be $10-$20 apart without anyone making a mistake.

Neither method is wrong—but you should know which one your landlord uses. Our calculator uses actual days because that's the most precise approach.

You'll usually get prorated rent when:

• Your lease officially starts mid-month
• You negotiate an early move-in date
• Your lease end date falls before month's end
• Your state requires it (California, for example, generally does)

Don't count on proration when:

• Your lease says "full month payments required regardless of occupancy"
• You're breaking your lease early (different from a scheduled end date)
• Your landlord has a strict no-proration policy (more common for move-outs)

The move: Read your lease before asking. If proration isn't mentioned, bring it up during negotiations—before you sign. "Will rent be prorated if I move in on the 15th?" is a reasonable question that any decent landlord will answer clearly.

Run the numbers before you meet. Walk into lease signing already knowing what your prorated amount should be. If the landlord's figure matches, great. If it's off, you can ask about it without seeming confrontational—"I calculated $660, but this says $700. Can you walk me through the math?"

Ask which method they use. If there's a small discrepancy, it's probably the 30-day vs. actual-days thing. Just ask. Most landlords will explain their approach, and you'll both know you're on the same page.

Get the full breakdown in writing. Before handing over any money, ask for an itemized list: prorated rent, next month's rent, security deposit, any fees. Compare it to what you calculated. This takes five minutes and prevents hundred-dollar misunderstandings.

Document your move-out. On your last day, take timestamped photos of the empty apartment and keep a copy of your written notice. If there's ever a dispute about your final rent or security deposit, you'll be glad you did.

Look up your state's rules. Tenant protection laws vary wildly. Some states require proration; others leave it entirely to the lease. A five-minute search for "[your state] prorated rent tenant rights" can tell you where you stand before any negotiations.