Prorated Rent Calculator
When a tenant moves in or out partway through the month, they owe rent for the days they actually have the place. This calculator figures that amount for a move-in or a move-out date, using either of the two common billing methods, and shows every step of the math so you can put it in writing.
Enter the monthly rent and a date to see the prorated amount and the math behind it.
How proration works
There are two common ways to compute a daily rate, and they give slightly different answers:
- Days in the actual month. Divide the monthly rent by the number of days in that specific month (28, 29, 30, or 31), then multiply by the days the tenant is responsible for. This is the most common method.
- 30-day month (sometimes called the "banker's month"). Divide the monthly rent by a flat 30 regardless of the month, then multiply by the billable days. Some leases and some landlords use this because the daily rate stays the same all year.
Neither method is more correct than the other in general. What matters is that your lease says which one you use, and that you apply it consistently. If the lease is silent, the days-in-the-actual-month method is the safer default because it is the easiest to justify.
Not legal advice. This calculator is general math, not legal advice. A few states and cities have rules about how proration must be computed or when prorated rent is due. Check your lease and your local law, and put the method you used in writing.
Common questions
Do landlords have to prorate rent?
Usually it comes down to the lease, not a statute. Most leases either state a proration method or are silent, and most landlords prorate move-ins as a matter of fairness and getting the deal done. For move-outs it depends on the lease and how proper notice was given. If you are unsure what applies where you are, check your state's landlord-tenant rules.
Which method should I use — actual days or the 30-day month?
If your lease names a method, use that one. If it doesn't, days-in-the-actual-month is the common default and the easiest to explain to a tenant. The 30-day method's advantage is a constant daily rate; its drawback is that in a 31-day month the two methods disagree by about 3 percent.
Does the move-in day itself count as a billable day?
Yes, in the standard convention. If the tenant gets keys on the 12th, they are responsible for the 12th through the end of the month. Same on the way out: the move-out day counts through that day. This calculator uses that convention and says so in the math it shows.
Is prorated rent due at move-in or with the second month?
Both patterns exist. Many landlords collect a full first month plus deposit up front, then prorate the second month. Others collect the prorated amount plus deposit at move-in. Either is fine — write whichever you choose into the lease so there's no argument later.