What does a SARON mortgage cost?
A SARON mortgage charges the current reference rate plus a fixed bank margin. Enter your amount, today's SARON and the margin to see the monthly interest.
SARON resets continuously, so this monthly figure moves with the rate. It excludes amortization.
Lenders test affordability at an imputed 5%, not today's SARON. Check whether the home clears that rule.
Open the affordability calculatorIndicative only. Your actual rate depends on your bank's margin and the SARON over each billing period, and most contracts floor SARON at 0%. Not a mortgage offer.
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What SARON is
SARON (Swiss Average Rate Overnight) is the reference interest rate for the Swiss franc, based on real overnight transactions in the secured money market. It replaced LIBOR at the end of 2021. A SARON mortgage charges the compounded SARON over each billing period plus a fixed margin your bank sets when you sign.
SARON vs a fixed-rate mortgage
A fixed-rate mortgage locks one rate for the whole term, giving certainty but usually a premium. A SARON mortgage follows the money market: cheaper when rates are low, but the monthly cost can rise if the SNB raises its policy rate. Historically SARON mortgages have often been cheaper over time, at the cost of month-to-month uncertainty.
How the margin works
Your effective rate is SARON plus the bank's margin. SARON moves with the market, but the margin is fixed for the term of the agreement and is where banks compete. A margin of 0.7% versus 1.1% on a CHF 750,000 mortgage is a difference of CHF 3,000 a year, so it is worth comparing offers.
Why the 0% floor matters
When SARON is negative, as it has been around the SNB's zero-rate periods, most mortgage contracts floor the SARON component at 0%. You then pay just the margin. This calculator applies that floor, so entering a negative SARON still shows the margin as your minimum rate.
Frequently asked questions
What is the current SARON rate?
As of June 2026 SARON sits near 0%, in line with the SNB policy rate of 0%. It changes daily, so check the live figure at SIX before relying on it.
How is a SARON mortgage rate calculated?
It is the compounded SARON over the billing period plus your bank's fixed margin. Most contracts floor the SARON part at 0%, so your minimum rate is the margin.
Is a SARON or fixed mortgage cheaper?
It depends on rate movements. SARON is usually cheaper when rates are low or falling but exposes you to increases; a fixed rate costs a premium for certainty. There is no universally cheaper option.
Can my SARON rate change every month?
Yes. SARON resets continuously and your interest is billed per period (often quarterly), so the cost moves with the market. The margin stays fixed.
What margin should I expect?
Bank margins typically range from about 0.7% to 1.1%, depending on the lender, the loan-to-value and your profile. It is the main thing to negotiate.