The Swiss mortgage reference rate is at a record-low 1.25%. If your rent is still based on a higher rate, you can request a reduction. Enter two things to find out.
Swiss net rents are tied to the mortgage reference rate. When it falls below the rate your rent is based on, you can ask for a reduction (Art. 270a OR). Each 0.25% step is worth about 2.91%.
Your landlord may offset part of it: up to 40% of inflation (CPI) since your last adjustment, plus a general cost allowance (~0.5%/year). We subtract both to show a realistic estimate.