# Rent Increase Calculator (Kappungsgrenze)

> Check how much the rent may be increased under §558 BGB — limited by the Kappungsgrenze cap and the local comparative rent.

Canonical: https://www.investbud.de/en/calculators/mieterhoehung
Last updated: 2026-10-28

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, or 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 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: text form and justification (§558a BGB), the tenant's consent period until the end of the second calendar month after receipt (§558b BGB) and the waiting periods. The request can be made at the earliest one year after the last increase, and the rent must have been unchanged for 15 months when the increase takes effect. The 15% cap only applies in areas designated by state government ordinance, each time for at most five years (§558(3) BGB). 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.

## Practical Tips

- A rent increase request under §558 BGB can be made at the earliest one year after the last increase, and the rent must have been unchanged for 15 months when it takes effect. It must be justified in text form, e.g. with the rent index.
- Whether the 15% cap applies is set out in your federal state's Kappungsgrenze ordinance. Such ordinances apply for at most five years at a time.
- For investors, the gap between current rent and comparative rent is a key metric: it shows a property's rent growth potential within the existing tenancy.

## Frequently Asked Questions

### What is the Kappungsgrenze?

The cap under §558(3) BGB limits rent increases in ongoing tenancies to 20% within three years. In areas with a tight housing market, designated by state government ordinance for at most five years at a time, it is 15%.

### Can the rent be raised up to the comparative rent?

Yes, but only as far as the cap also allows. The lower of the two limits always applies. If the current rent is already at the level of the comparative rent, no increase under §558 BGB is possible.

### Where do I find the local comparative rent?

Usually from the municipality's rent index (Mietspiegel). Municipalities with more than 50,000 inhabitants must produce and publish one (§558c(4) BGB). Other accepted justifications are information from a rent database, a reasoned opinion by a publicly appointed and sworn expert, or three comparable flats (§558a(2) BGB).

### Does the cap also apply to new lettings?

No. The cap does not apply when re-letting. Instead, the rent brake (Mietpreisbremse) may apply, limiting the rent at the start of the tenancy in areas designated by ordinance to the local comparative rent plus 10% (§556d BGB).

### How often can the rent be increased?

A request under §558 BGB can be made at the earliest one year after the last increase, and the rent must have been unchanged for 15 months when the increase takes effect. In addition, the cap applies over the rolling three-year period.