Hello Thikozett35
Welcome to the SBB Community.
Your question causes a few question marks at my end.
What are your plans for Grindelwald, Terminal? Going up to Jungfraujoch, perhaps? In Switzerland, you can purchase any public transport ticket using the SBB Mobile app. It will suggest you the best ticket option.
So if your plans are to go up to Jungfraujoch, then purchase the return ticket accordingly; you can purchase the whole trip in one ticket. It is valid via Grindelwald Terminal and/or Lauterbrunnen. In addition, the Swiss Half Fare Card is strongly recommended.
If you need a ticket to Grindelwald Terminal and back from Lauterbrunnen, then purchase two single tickets, either full fare or half fare, the latter if you hold the Swiss Half Fare Card.
To simply answer your question:
- Interlaken Ost to Grindelwald Terminal, one way, full fare: CHF 11.
- Lauterbrunnen to Interlaken Ost, one way, full fare: CHF 7.80.
Kind regards,
Roland