Pro-Rata Rent Calculator

Pro-rata rent: formula and use cases

When a tenant occupies a place for only part of a month, the rent gets split by the days they were actually there. The usual formula is pro-rata = (monthly rent / days in month) · days occupied. Most contracts count the real number of days in the reference month (30 or 31, or 28 and 29 in February), though a few stick to a flat 30-day base. Read the lease clause to be sure. Take a R$ 2,000 rent in a 30-day month with 10 days occupied: that comes to R$ 666.67.

IPTU and condo fees get split the same way whenever the lease hands those costs to the tenant. The Tenancy Law (Lei do Inquilinato 8.245/1991) never spells out pro-rata as a requirement, but the practice has settled in across the market anyway.

Brazilian context

Proptechs like QuintoAndar and Loft run the pro-rata math automatically on move-in, move-out and tenant swaps that happen within a single month. If the tenant breaks the lease early, the penalty can reach three months of rent, but it shrinks in proportion to how much of the contract has already run. That reduction is itself a pro-rata calculation, and the Tenancy Law governs it. Property managers lean on the same approach to square owner payouts when someone moves in halfway through the month.

FAQ

Should I use 30 days or the real number of days in the month? Go with whatever the lease specifies. When it says nothing, the real day count is the safer bet, since that's how civil-law tradition handles daily proration.

Does the move-out day count? Yes. By convention it counts as an occupied day, because the tenant usually keeps the keys until the day is over.

Can the landlord refuse pro-rata? In practice, no. Billing a full month for partial occupation reads as abusive to most people, and it wouldn't hold up in a consumer-rights dispute.