Vacancy Math: How Much Does an Empty Unit Really Cost Per Month?

An empty unit does not feel like it is costing you anything. Nothing is breaking. Nobody is calling. The mailbox is quiet. That is exactly why vacancy is the most underestimated line in small-portfolio ownership — it bleeds silently, and by the time you notice, the money is already gone. So let's price it. Not with figures I made up, but with your figures. Get a piece of paper. This takes about ten minutes and you will not look at a vacant month the same way afterward.

Step one: your cost per vacant day

Start here, because everything else scales off it.

Take [YOUR MONTHLY RENT] and divide it by 30. That is your baseline cost per vacant day. Write it at the top of the page and circle it.

That number is the floor, not the total. It only captures rent you are not collecting. It ignores everything the vacancy actively costs you on top of that, which is where owners consistently underestimate the damage.

Step two: the carrying costs that do not stop

When a unit is occupied, some expenses are covered by the tenant or absorbed by the rent. When it is empty, they land directly on you. Write down your own figure for each of these, per month:

Utilities you now pay because there is no tenant to pay them — heat you have to keep running so the pipes do not freeze during a Hudson Valley January, electric for showings, water. Snow removal and lawn care, which do not pause. Insurance, which may be treated differently once a unit has been unoccupied past a certain point, so check your policy language before you assume your coverage is unchanged. Your mortgage payment and your taxes, which are entirely indifferent to whether anyone lives there.

Add those up. Call it [YOUR MONTHLY CARRYING COST].

Step three: the one-time costs of getting it filled

These are real vacancy costs even though they feel like separate line items. Turnover labor and materials: paint, cleaning, carpet or floor work, the repairs you deferred while it was occupied. Marketing: photography, listing syndication, whatever you spend to get attention. Showing time, priced at your own hourly value — this is the line owners always leave blank and it is often the largest one. Screening and application processing. New keys, new locks.

Add those up. Call it [YOUR TURNOVER COST].

The whole formula

Now put it together for a vacancy of any length:

Total vacancy cost = ( [YOUR MONTHLY RENT] ÷ 30 × [DAYS VACANT] ) + ( [YOUR MONTHLY CARRYING COST] ÷ 30 × [DAYS VACANT] ) + [YOUR TURNOVER COST]

Run it three times. Once for a fast turn, once for the length of your last actual vacancy, and once for a bad one. The spread between those three results is the number that should drive how you think about pricing, prep, and renewal effort — because that spread is what is genuinely at stake, and it is usually far larger than the fee conversation people spend all their energy on.

What to do with the number

Two things become obvious once you have it in front of you.

First, a rent reduction that fills the unit quickly is frequently cheaper than holding out for a higher number while the daily cost accumulates. Compare the annual value of the extra rent you are holding out for against the per-day cost of the days you spend waiting. The arithmetic is unsentimental. Run it before you reject an application-ready prospect over a small gap.

Second, renewal effort is the highest-return work you can do. Every renewal you earn is one full turnover cost and one full vacancy period you never pay. Nothing else in small-portfolio management pays back that reliably.

Do one thing today: fill in the top line. Your rent divided by 30. Write it on a sticky note and put it on the file for the property. That single number, sitting where you can see it, changes how quickly you return a prospect's call.

CTA: Download the vacancy-cost calculator. It is the formula above as a fillable sheet, blank, ready for your own numbers.