Part of the topic: 🏠 Home, energy & car
Index rent calculator (Indexmiete)
Enter your current net cold rent, the consumer price index (CPI) at the last rent change and the current CPI. The calculator shows the maximum new rent and from when it may be charged.
Voluntary support · Thank-you gift: our checklist PDF · Secure checkout via Digistore24 (Apple Pay, Google Pay, PayPal, card)
🔒 Runs entirely in your browser – nothing you enter is uploaded or stored.
How to use it
- Enter your current net cold rent.
- Enter the CPI value at your last rent change (from your contract or the previous letter) and the current value.
- Read the maximum new rent and the date from which it is due.
Last checked: October 2026 · Based on: § 557b German Civil Code; consumer price index (2020 = 100), Destatis, September 2026. Found a mistake? Use the form below – we fix confirmed errors and update the date.
Frequently asked questions
How is an index rent increase calculated?
New rent = old rent × current CPI ÷ CPI at the last change. Example: €800 × 126.6 ÷ 121.9 = €830.84.
How often can an index rent be raised?
At most once a year – the rent must remain unchanged for at least 12 months between two increases.
From when do I have to pay the higher rent?
From the beginning of the second month after you receive the letter. A letter received on 15 October means the new rent from 1 December.