When a lease starts or ends mid-month, you pay only for the days you occupy. The idea is simple; the arguments start over how to turn a monthly rent into a daily rate. This calculator applies the three conventions in use and shows them side by side, so you can check a landlord’s figure or agree one in advance.
How it is calculated
- Days occupied: for a move-in, from the move-in date through the last day of the month, both included. For a move-out, from the 1st through the move-out date.
- Daily rate, by method: rent ÷ days in that month (28–31); or rent × 12 ÷ 365; or rent ÷ 30.
- Prorated rent = daily rate × days occupied.
Example
Rent $1,800, moving in on the 20th of a 30-day month: 11 days occupied. Days-in-month: $60.00 a day, $660.00. Days-in-year: $59.18 a day, $650.96. Thirty-day month: $60.00, $660.00. In a 31-day month the first method gives $58.06 a day and $696.77 for 12 days, while the 30-day method overcharges slightly because it pretends the month is shorter.
Which method applies
Check the lease first; many state a method. A few US states prescribe one in statute for certain situations. Where nothing is specified, days-in-month is the most common and is what most property-management software defaults to. The days-in-year method produces a single daily rate for the whole year, which some landlords prefer for consistency. The 30-day method is a holdover from paper accounting and is slightly unfair in 31-day months.
Other partial-month charges
Utilities, parking and pet rent included in the rent are usually prorated the same way. Security deposits are not prorated. If the first month is prorated, the lease should say whether the second month is a full month; usually it is.
Frequently asked questions
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 days you occupy. For $1,800 in a 30-day month moving in on the 20th: $60 × 11 = $660.
Do I pay for the move-in day?
Yes. The move-in day counts as an occupied day. For a move-out, the move-out day counts too, since you have the keys that day.
Is prorated rent based on 30 days or the actual month?
Either, depending on the lease. The actual-days method is most common; some leases use 30 days or a yearly daily rate. The table shows all three so you can compare.
Can a landlord refuse to prorate rent?
They can charge a full month if you agree to it in the lease, but most prorate as standard. If a lease starts mid-month with full rent, it is worth negotiating before signing.
Sources
By Calcelate Team. Formula from the sources above.
- 2026-09-14 · Formula and texts checked