While technically possible, visiting Zermatt as a day trip from Zurich is an extremely long and exhausting endeavor. The journey by train takes approximately 3 hours and 15 minutes each way, involving a transfer in Visp. This means you will spend at least 6.5 to 7 hours of your day just in transit. If you leave Zurich at 7:00 AM, you arrive in Zermatt around 10:15 AM. To catch a reasonably timed train back, you would likely need to leave by 5:00 PM, giving you only about 6 or 7 hours in the village. This barely leaves enough time to take the Gornergrat Bahn or the Matterhorn Glacier Paradise cable car—the two main highlights—without rushing. Considering the high cost of Swiss rail tickets (often over 250 CHF round-trip without a half-fare card), most travel experts recommend staying at least one night in Zermatt to truly enjoy the car-free atmosphere and ensure you have a clear weather window to see the Matterhorn. If you are determined to do it in a day, start as early as possible and check the mountain webcams before you leave Zurich.