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The Mietpreisbremse caps the rent for newly signed leases: at the start of the tenancy, the net cold rent may be no more than 10 % above the local reference rent (§ 556d ff. of the German Civil Code). This calculator is based on Dortmund's official rent index 2025/2026 (valid 01 Jan 2025 to 31 Dec 2026). Dortmund rent index 2025/2026

Since 1 March 2025 Dortmund has been part of the area covered by North Rhine-Westphalia's tenant protection ordinance. Rent control therefore applies to leases signed on or after that date. It does not apply to older contracts.

It is the usual net cold rent for comparable flats, that is the rent excluding heating and operating costs as well as any furniture or parking surcharges. The starting point is the average for the building's age class in the rent index; depending on size, fittings, condition and location, additions or deductions apply.

Essentially two cases (§ 556f BGB): new builds first used and let after 1 October 2014, and extensively (near-new-build) modernised flats. For those, the rent can be agreed freely. Beyond that, tenancy law does not apply at all to housing for temporary use or to student halls of residence (§ 549 (2) and (3) BGB). Every other flat is covered by rent control, even where the rent index does not map it.

Yes, but differently: with a stepped rent (Staffelmiete) every single step has to stay within the limit (§ 557a (4) BGB). The second or third step can therefore be unlawful even though the initial rent was fine. With an index-linked rent (Indexmiete) only the initial rent is measured against rent control; later adjustments follow the consumer price index (§ 557b (4) BGB). This calculator always checks the rent at the start of the tenancy, for stepped rents therefore the first step.

Besides rent control, the tenant protection ordinance contains two further instruments: the capping limit (existing rents may rise by at most 15 % instead of 20 % over three years) and the extended notice protection period (eight instead of three years after conversion into condominiums). This calculator only checks rent control at the start of the tenancy.

Important first: these flats are not exempt from rent control, it still applies. The local reference rent simply cannot be derived from the rent index, so the result stays a rough guide and an individual assessment is worthwhile. Dortmund's rent index applies to flats from 20 to 145 m² built up to and including 2019. It leaves out furnished flats, flats in one- or two-family houses and substandard flats, that is those without a toilet inside the flat or with a toilet not fitted by the landlord.

The starting point is the average for the building's age class in Dortmund's rent index. On top of it come the additions and deductions for size, location, fittings, condition and modernisation; multiplied by your floor area, that gives the local reference rent. Plus 10 % gives the permitted maximum rent. That is the threshold above which you can object. The rent index also states a range for every age class within which rents still count as customary. Mietlupe deliberately works with the average, because it represents the typical case. A landlord may argue that their flat sits higher in that range because of features the rent index does not capture. The maximum rent then rises too.

If the previous tenant's rent was already above the permitted maximum, the landlord may keep charging it (§ 556e BGB). That can flip the outcome. But they may only rely on it if they informed you about that rent before the contract was signed, unprompted and in text form. If they failed to, the protection only kicks in two years after they provide that information (§ 556g (1a) BGB). If you don't know the previous rent, Mietlupe calculates without that protection.

The construction year is often in the lease, the energy certificate or the listing; otherwise the property management can help. Without it there is nothing to calculate, because it determines the age class. You may ask your landlord for the previous rent. They must disclose the facts they base a higher rent on (§ 556g (3) BGB). Until then, tick “I don't know” in the calculator; Mietlupe then leaves out the § 556e protection.

No. The rent index only takes fittings and modernisations into account if they were provided or carried out by the landlord. If you laid the parquet yourself or renewed the bathroom at your own expense, no surcharge may be applied. Answer “No” in those cases.

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You can object to the excessive rent to your landlord in text form (e.g. by e-mail). You don't have to back it up with figures, but the objection has to reach them, so keep a record of sending it. From the moment it arrives you can reclaim overpaid rent; there is no claim for the period before, and claims lapse three years after the end of the year in which they arose. Before that, use your right to information: the landlord must state the facts they base a higher rent on (§ 556g (3) BGB). For a binding assessment, contact a tenants' association or the consumer advice centre (Verbraucherzentrale NRW).

These are two levels above rent control that apply independently of it, including to older contracts and to flats exempt from rent control. If the rent is more than roughly 20 % above the local reference rent and the landlord is exploiting a shortage of housing, it can amount to excessive rent (§ 5 WiStG), a regulatory offence. From roughly 50 % above, criminal rent profiteering (§ 291 StGB) comes into play. Both depend on the individual case; Mietlupe only shows whether your result falls into that range.

No. The result is a non-binding initial assessment based on Dortmund's rent index and knows neither your lease nor the particulars of your flat. Only a tenants' association or a lawyer specialising in tenancy law can assess it bindingly.