Zürich / Zurich to St. Moritz by train

The connecting time between trains at Chur station will only be around 4 mins, but this is Switzerland so making the connection can be virtually guaranteed.

To enable a stress-free transfer at Chur station. the train on to St. Moritz will depart from the opposite side of the same platform that the train from Zurich will have arrived at, so all you will have to do is walk across the platform from one train to the other.

If you will be travelling with any type of rail pass, including Saver Day Passes, you can just jump on the train to St. Moritz.
If you opt to travel with tickets, definitely book tickets for the end2end journey on SBB's booking service you won't have time to book tickets for the next RhB train to depart, on arrival at Chur station.

Though:

• if you will be travelling with a 2nd class ticket/rail pass
• time is on your side
• and you want to experience the best of the journey between Chur and St. Moritz
  then it can be a good idea to hang back and take the next train on from Chur.
  With only 4 mins to elapse before departure, 2nd class on the RhB train to St. Moritz can be crowded, so you'll be lucky to find a window seat if you rush to board in Chur.

Also if you see a Glacier Express train at Chur station, your tickets/passes won't be valid on the Glacier Express, but regular coaches, in which your tickets/passes will be valid, may be attached to the Glacier Express train.
So you may need to hurry along the (gleis) platform/track to find them.

Booking Tickets:

Tickets can be booked online for this end-to-end journey which involves taking a SBB train + the train(s) on to St.Moritz which are operated by RhB.

‘Individual tickets’ can be used on any train(s) on your travel date, but they tend to be comparatively expensive.

Supersaver tickets are cheaper, the portion of the journey by the SBB train can be discounted by up to 50%, but these tickets are train departure specific.

If you book a Supersaver ticket and a flight delay etc, causes you to miss a train you are booked on to, you will have to book another full-price ‘Individual Ticket(s).
You can then apply for a refund of the Supersaver ticket, but the application costs CHF 10.

Hence it’s worth comparing the ticket price of a journey with the price(s) of those Saver Day Passes; they might save you money and can also allow for a less stressful journey.

Using Saver Day Passes:

Now that the Swiss Transfer tickets have been discontinued a Saver Day Pass may save you money, if you can book at least a couple of weeks ahead (usually), so that you can obtain the pass at a discounted price.

They can be cheaper than tickets for the end-to-end journey, though they are more likely to be a money saver if you will be making a day return trip between Zurich and St.Moritz even if you can book in advance.

They can be used on;

• the trains between Zurich Fughafen/Airport and Zurich HB station
• the trains between Zurich HB and Chur
• the trains between Chur and St. Moritz.

They are not train specific, so can still be used in the event of a journey to Switzerland being delayed.
Though they’re only valid for one day’s travel, the clue is the name, so if you will be travelling back on another date, you’ll need to purchase another Saver Day Pass for your return journey.

However, they need to be booked at least a day ahead of your travel date, so won't be an option if you book tickets at the station on arrival in Switzerland.
They're also cheaper the further ahead that you book.