Yes almost all trains in Switzerland are included !

If you're doing a longer day trip, using a pass day will be worthwhile but for a short hop into Bern buy regular tickets

As you're around Bern you need to take a boat on Lake Thun and Lake Brienz, they're included.

The major drawbacks of Interrail vs Swiss Travel Pass :

- STP covers journeys from Interlaken to Wengen, Lauterbrunnen and Grindelwald while Interrail only gives 25% discounts

- only trains are included in Interrail (with the mentionned boat exception). So no buses or trams around Bern as an example

Both passes give 25-50% discount for mountain railways. 

For Interrail validity see : https://www.interrail.eu/content/dam/miscellaneous/Map%20of%20Switzerland_SBB.JPG

Do not hesitate for questions. Switzerland is an incredible country for train travels (I might be a bit biased...)

S-Bahn mellan Schüpfen och Bern körs av BLS och där gäller Interrail. På S-Bahn som körs av RBS (orangea smalspårs-tåg) ger Interrail 50% rabatt.

Njut av tågresandet i Schweiz, som är mitt andra hemland.

Här finns information om vilka tågbolag som ingår i Interrail i Schweiz. 

https://www.interrail.eu/en/plan-your-trip/tips-and-tricks/trains-europe/railway-companies/swiss-railway-companies-included

@AnnaB per the map it looks like RBS trains are also included (Bern - Jegenstorf - Solothurn)

Thank you! The Interrail pass for Switzerland is €229 for 6 days (I am staying 8 days) for 2nd class, for 1 adult, if I’m not wrong? Hopefully this will also be the price when I buy it which I will do later. This is the first time using Interrail. 

The train from Geneva Airport to Bern is 56 CHF, and then 56 CHF again to get back there the day I am traveling home. Just that alone is 112 CHF. One of the days I want to make a day trip to Liechtenstein via Buchs SG (one of the only 3 European countries I still haven't been to so I am interested in going there) which is 152 CHF two way. That's 264 CHF for these trains mentioned so even there the Interrail pass will be much cheaper than buying individual train tickets. So it’s just a nice bonus if it also includes the local trains to Bern so thanks for confirming that!

I would like a day trip to Fribourg and Montreux in the French-speaking part of the country and those trains are included in Interrail. I would also like a day trip to Grindelwald and Lauterbrunnen, the train to Interlaken seems to be included but the trains from there to Grindelwald and Lauterbrunnen are very cheap (I looked it up), so not going to get the STP just for that. 

There are both RBS and SBB trains from Bern to Solothurn. The SBB trains are included and the RBS trains are not included, which is tricky to show on a map.

I was in contact with RBS customer service last spring to check if Interrail was valid between Bern RBS and Schoppyland RBS and the answer was that Interrail gave the same discount as as 1/2 tax Abo.

Yes a Interrail pass will be worth it !

Those would be the additional costs :

- Interlaken - Grindelwald - Lauterbrunnen - Interlaken should cost 20.85 CHF (incl. 25% discount)

- Liechtenstein bus day card 12 CHF (valid from Swiss train stations like Sargans or Buchs)

Use SBB app -> very helpful. Simply be aware that it first shows half-fare prices (as the half-fare card is used by millions of Swiss)

@AnnaB Seems a bit weird to me as it clearly is valid per the map (RBS run Bern - Jegenstorf - Solothurn services)... but again might be a case where customer service, SBB map and Interrail website don't match. Maybe I'll ask next time I go to Bern (if I remember...)

(and they sell Interrail passes at their stations)

Does the Interrail prices change by popularity, is there any incentive to buy the pass very early? As I said I am new to this and I never used it before because I usually travel in countries where individual train tickets are cheaper than a pass. 

Interrail passes always have the same price and cannot sell out. There's only a small price hike at the start of each year

You can buy the pass at any time, when you've bought it you have 11 months to activate it

Maybe there will be a sale but it's unlikely until summer (+ it's usually for Global Passes only)

Do they still? SBB don't sell paper passes anymore since this year.

I have reported this to Interrail but things change slowly. 

Here's the reply from RBS customer service:

Guten Tag Frau Björnson

Besten Dank für Ihre Nachricht.

Beim RBS ist das Interrail-Ticket nur ermässigt gültig. Das bedeutet, für Fahrten auf dem RBS-Streckennetz lösen Sie und Ihre Familie jeweils ein Ticket zum ermässigten Preis (sogenannten Halbtax-Preis).

Ich wünsche Ihnen frohe Ostern und einen schönen Aufenthalt in der Schweiz.

Beste Grüsse

I don't know. Yeah when I bought my pass in January at a SBB ticket counter, I was the first one to get a mobile pass. It was still new to them :)