Is your rent too high?

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.

The rent index applies to flats from 20 to 145 m² and only publishes construction-year classes up to and including 2019 – for newer buildings no reference rent can be derived from it. Further exemptions are new builds (first let from October 2014), extensively modernised flats, furnished flats, flats in one- or two-family houses, and substandard flats (no toilet inside the flat, or a bathroom not fitted by the landlord). In those cases the calculator is only a rough guide.

If the previous tenant's rent was already above the permitted maximum, the landlord may keep charging it (§ 556e BGB). That can change the outcome, which is why we ask. What counts is the net cold rent the previous tenant owed in the final year of their tenancy; increases agreed during that final year are disregarded. You may ask your landlord for the figure – and they must disclose it unprompted if they rely on it (§ 556g (1a) and (3) BGB). If you don't know it, Mietlupe calculates without that 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.

You can object to the excessive rent to your landlord in text form (e.g. by e-mail) and, from the moment that objection reaches them, you may be able to reclaim overpaid rent. There is no claim for the period before it – so it pays not to wait too long. For a binding assessment, contact a tenants' association or the consumer advice centre (Verbraucherzentrale NRW).

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.

No. The result is a non-binding initial assessment based on Dortmund's rent index. For a binding evaluation, contact a tenants' association, a lawyer specialising in tenancy law, or the consumer advice centre (Verbraucherzentrale NRW).