The rule for a US licence
Switzerland accepts a valid foreign license for up to 12 months. An IDP is not legally required for a tourist visit but is recommended as a translation.
If you are driving on to Italy, Austria, or France, note that those countries do require an IDP, so a Swiss-centered trip that crosses a border may still need one.
Live in Switzerland?
A licence issued in Switzerland is what you drive on at home - an IDP translates a foreign licence, so it does not apply to you here. If your licence is from somewhere else, check that licence country: the rule depends on where the licence was issued, not only on where you are driving.
At the rental counter
Swiss agencies accept a US license. Remember the motorway vignette, which is required for Swiss motorways and usually already fitted to rentals.
What the permit covers
An International Driving Permit is a translation of your licence into a standard multilingual booklet, issued under the 1949 and 1968 road traffic conventions. It is not a licence, and it is never valid on its own: you carry it with your own licence, and police expect to see both.
It is issued against the vehicle classes already on your home licence, and it never adds one. If your licence does not cover motorcycles, an IDP does not let you ride a scooter in Switzerland; if it does not cover a heavier vehicle, the permit will not cover a camper or a minibus either. The permit restates what you already hold, in a form the local authorities can read.
Driving in more than one country?
Check every destination on your trip at once - Switzerland is already filled in.
Check your tripOther destinations
Informational only, not legal advice. Requirements change and vary by length of stay, rental company, and vehicle class. Always confirm with the destination's embassy or your automobile association before you drive.