In existing tenancies, German landlords cannot raise the rent at will: §558 BGB only allows increases up to the local comparative rent (ortsübliche Vergleichsmiete) and additionally by at most 20% within three years — 15% in areas with a tight housing market (the Kappungsgrenze cap). Our calculator shows which of the two limits applies and how much room there actually is. It is a simplified orientation and does not replace legal advice.
How to use this calculator
The calculator checks both statutory limits and applies the stricter one:
- Step 1: Enter the current net cold rent.
- Step 2: Enter the net cold rent that applied three years ago — it is the basis of the cap.
- Step 3: Enter the local comparative rent for the flat, e.g. from the local rent index (Mietspiegel).
- Step 4: Select whether the flat is located in an area with a tight housing market — there the reduced cap of 15% applies. Whether your city qualifies is set out in your federal state's Kappungsgrenze ordinance.
Understanding the results
The permissible increase is the minimum of two limits:
- Upper limit under the cap: the rent from three years ago plus 15% or 20%.
- Maximum permissible new rent: the lower of the cap limit and the local comparative rent — more is not enforceable under §558 BGB.
- Permissible increase: the difference between the maximum permissible new rent and the current rent.
- Assessment: which of the two limits constrains the increase in your specific case.
What this calculator does not cover
This calculator only deals with rent increases up to the local comparative rent in ongoing tenancies under §558 BGB. It does not cover the rent brake (Mietpreisbremse) for new lettings, increases after modernization (§559 BGB), index-linked or stepped rent contracts, or the formal requirements of a rent increase notice — such as the justification requirement, the tenant's consent period and the 15-month waiting period since the last increase. In tight housing markets, the 15% cap only applies while the respective state ordinance is in force; the designated areas change regularly. Large cities such as Berlin, Munich, Hamburg, Cologne or Frankfurt are typically covered. Always check your specific case against your federal state's current ordinance and seek legal advice when in doubt — this calculator is an orientation aid, not legal advice.
Tips
- •A rent increase under §558 BGB can take effect at the earliest 15 months after move-in or the last increase, and must be justified, e.g. with the rent index.
- •Whether the 15% cap applies is set out in your federal state's Kappungsgrenze ordinance — the area lists are updated regularly.
- •For investors, the gap between current rent and comparative rent is a key metric: it shows a property's realistic rent growth potential.