Prorated Rent Calculator

Paying for part of a month

Leases start on the first of the month in theory. In practice people move on the eighteenth, because that is when the previous tenant left or the van was available or the job started.

So somebody has to work out what a fortnight of a monthly rent is worth. That is prorating, and this calculator does it.

Three inputs. Whether you are moving in or out, the date it happens, and the full monthly rent. It works out how many days you occupy the place that month, prices them, and returns the figure.

Simple enough. Except that there is more than one defensible way to price a day of rent, they give different answers, and almost no lease says which one is being used.

Which days you are charged for

Before the price, the count. The convention here is standard and worth stating because it decides one full day either way.

Moving in. You pay from and including your move-in date to the end of the month. Move in on the 18th of a 31 day month and that is 14 days, counting the 18th itself.

Moving out. You pay from the first of the month up to and including your move-out date. Leave on the 18th and that is 18 days.

The rule underneath both is that the day you move counts as a day you occupied. That is the usual arrangement and it is the one this calculator applies. It is not universal, and some leases treat the move-out date as the day you are already gone, which shaves one day off. Worth a glance at the wording if the difference matters.

Three ways to price a single day

Now the part that varies. Once you know how many days, you need a price per day, and there are three in common use.

This calculator uses the first one. Days in that specific month. It looks up how many days the month actually has and divides the rent by that.

On a rent of 30,000 with 14 days occupied in July, the three come out as:

Four hundred and fifty odd apart on the same fourteen days, which is not enormous but is real money and is entirely a matter of which convention somebody picked.

None of the three is wrong. The days-in-month method has the property that a full month always costs exactly the monthly rent, which the other two do not. The fixed 30 method is simplest and is what a lot of property managers use. The annualised method is the fairest across a whole year and is the one most likely to appear in a commercial lease.

If your landlord's figure differs from ours, this is almost certainly why, and now you can work out which one they used: divide their figure by the number of days and see which daily rate it matches.

Why moving in February costs more per day

Here is the consequence of the days-in-month method that catches people out, and it is not obvious until you see it side by side.

Because the daily rate is the monthly rent divided by that month's length, a day of rent costs more in a short month. Same flat, same rent, different price per day depending on when you move.

A day in February costs 10.7 percent more than a day in July.

Which flips the comparison with the other methods completely. Move in on the 18th of July and our method gives the lowest of the three answers. Move in on the 18th of February and it gives the highest:

Notice April, where the first two agree exactly, because April has thirty days and the two methods are the same thing that month.

None of this is unfair, it is just consistent. Under the days-in-month method you always pay the same share of that month's rent for that share of that month's days. But it does mean that if you have any say over the move date and the difference is worth anything to you, a long month is the cheaper one to arrive in the middle of.

Moving in on the eighteenth

Rent of 30,000, moving in on 18 July.

Step one, the days. July has 31 days. Moving in on the 18th means occupying the 18th through the 31st, which is 31 minus 18 plus 1, so 14 days.

Step two, the daily rate. 30,000 divided by 31 is 967.74.

Step three. 967.74 times 14 is 13,548.39.

So a little under half a month's rent for a little under half a month, which is exactly what you would hope.

Sanity check it the other way: 14 days out of 31 is 45.2 percent of the month, and 45.2 percent of 30,000 is 13,548. Same answer. If the figure you have been given is more than a whole month's rent, or more than the share of days you occupied, something has gone wrong.

Moving out on the same date gives the mirror image. The 1st through the 18th is 18 days, so 967.74 times 18, which is 17,419.35.

When one tenant leaves and another arrives

One more thing worth knowing, and it only shows up when you look at both sides of the same date.

Add the two figures above. The outgoing tenant leaving on 18 July pays 17,419.35. The incoming tenant arriving on 18 July pays 13,548.39.

Together that is 30,967.74, on a flat whose monthly rent is 30,000.

The landlord has collected one day of rent twice, because both conventions treat the 18th as a day the tenant occupied. On these numbers that is 967.74 of extra rent for a single changeover, or a little over three percent of a month.

It is not sharp practice and it is not usually deliberate. It falls out of two perfectly reasonable rules applied from opposite ends of the same day. But if you are the incoming tenant and you know the previous one moved out that morning, it is a legitimate thing to raise, and the usual resolution is that whoever actually had the keys overnight pays for the day.

The same logic in reverse leaves a gap if a lease treats both move dates as unoccupied, in which case nobody pays for the changeover day. Whichever way your lease is written, the fix is the same: agree explicitly who owns the transition day, in writing, before anybody moves.

Questions people ask

Do I pay for the day I move in?

Under this calculator, yes. Both the move-in and move-out dates are counted as occupied days, which is the usual convention. Some leases say otherwise, so it is worth checking the wording.

My landlord's figure is different from yours.

Almost certainly a different daily rate. Divide their figure by the number of days you occupied. If it comes to the rent divided by 30, they use a fixed month. If it comes to annual rent over 365, they annualise. If it matches rent divided by that month's days, something else is different.

Which method is fairest?

The annualised one is the most even across a whole year, since every day of the year costs the same. The days-in-month method has the advantage that a full month always costs exactly the monthly rent. Neither is standard everywhere.

Why does February cost more per day?

Because the monthly rent is divided by fewer days. On a 30,000 rent a February day costs 1,071.43 and a July day costs 967.74, a difference of 10.7 percent.

My tenancy is partial at both ends.

Run the calculator twice, once as a move in for the first month and once as a move out for the last, and add the full months in between at the normal rent.

Is the deposit prorated too?

No. A deposit is a fixed security amount held against damage and unpaid rent, not a charge for occupancy, so it does not scale with days. It is refundable at the end subject to the lease terms.

What about utilities and maintenance charges?

Those are usually prorated too, but by their own arrangement rather than by this calculation. Metered utilities are read on the day. Fixed monthly charges are often split the same way as the rent.

References

A note on why this page leads with methods rather than a single formula. Prorating a partial month is a matter of contract rather than statute in most places, which is precisely why several conventions coexist and why a lease that is silent on the point invites disagreement. What tends to be regulated is the surrounding tenancy, including deposits and notice, under local landlord and tenant law. The affordability framing, meaning what share of income a rent represents once the partial month is settled, follows the Department of Housing and Urban Development's cost burden standard.

1. U.S. Department of Housing and Urban Development, Office of Policy Development and Research, Defining Housing Affordability, HUD USER, on housing cost measurement and the 30 percent affordability threshold. https://www.huduser.gov/portal/pdredge/pdr-edge-featd-article-081417.html
2. U.S. Department of Housing and Urban Development, Office of Policy Development and Research, Rental Burdens: Rethinking Affordability Measures, HUD USER, on cost burdened and severely cost burdened households. https://www.huduser.gov/portal/pdredge/pdr_edge_featd_article_092214.html