On 14 September, flats advertised for rent in Warsaw were asking an average of 3,629 zł a month. In Łódź the same figure was 1,987 zł. A gap of 1,642 zł.

The numbers come from Znajdź Najem, which tracks around 157,000 active rental adverts across 34 Polish cities and publishes the totals under an open licence.

Most people read this study from the tenant's side, as a guide to where living costs less. We want to look at it from the landlord's.

The square metre is the honest comparison

Coming back to Warsaw and Łódź. On the whole flat, Warsaw asks about 83% more. Per square metre, about 55% more. The difference between those two numbers is flat size: the Warsaw adverts in this sample are for larger flats than the Łódź ones.

That matters if you own a small flat in Warsaw. Comparing your rent against 3,629 zł tells you almost nothing, because that average describes a bigger flat than yours. Divide your rent by your floor area and put the result next to 85 zł. It is the one figure here that compares like with like, across cities and across flat sizes.

What owners ask, and what tenants actually pay

Every number above is taken from adverts that were live on 14 September. Nobody has checked what those flats went on to rent for.

That pushes the average up. An overpriced flat stays on the board week after week and keeps being counted. A sensibly priced one is gone in days. So the pool you are measuring yourself against is thick with flats nobody wanted at that price.

The medians show it. Warsaw's median is 3,200 zł against an average of 3,629, which means half of all Warsaw adverts sit below 3,200.

Read the average as the top of the range, not the going rate.

The advert price is rent only

Every figure above is rent. The czynsz that goes to the building, and the utilities on top of it, electricity, water, heating, gas and internet, are billed separately and appear in none of these numbers.

That limits what a city-to-city comparison can tell you. Two flats advertised at the same rent can leave the tenant with very different monthly totals, depending on the building, how it is heated and how the meters are split. The gap between Warsaw and Łódź in the table measures rent alone.

For you it cuts both ways. Rent is the part you set and advertise. The charges arrive anyway, and they move on their own schedule.

Rents stopped rising. The bills underneath didn't

Asking rents across Poland are down 0.7% year on year, on Otodom Analytics' July report. Warsaw down 2.6%, Kraków and Wrocław down 3.6% each.

The charges went the other way. GUS has electricity up 12.9% over the year, refuse collection up 8.5%, solid fuel up 8.2% and water up 4.9%, in figures carried by forsal.pl.

A tenant budgets one monthly total, rent and charges together. When the charges take a bigger slice of it, the slice left for rent is what gets squeezed. That is the pressure sitting on the asking price.

Two things worth doing before your next renewal

Work out your own zł/m². Divide your rent by your floor area and put it next to your city's figure in the table. That is where you actually stand, and it takes two minutes.

Keep rent and charges as two separate numbers. They are moving in opposite directions right now, and one combined figure per month hides that completely. The charges decide how much a tenant can still afford to pay you in rent, so watching them over a year or two tells you where your own ceiling is heading. You can only see it if you have been recording both all along.

Hestium does that part for you. Every payment in and every cost out sits in one place, so what the flat actually earns once the costs are counted is a number you read off the screen in a few taps.