Transportation from Stockholm to Copenhagen

Usually flying into Copenhagen and home from Stockholm is about the same price as a round-trip to Copenhagen. When you search for your flights, make sure that you have chosen the multi-city option (as opposed to searching for two one-way flights). Otherwise, the main options for traveling from Stockholm to Copenhagen are the train (about 5 hours) or a flight.

It seems to be less expensive to fly in and out of Copenhagen vs. in to Copenhagen and out of Stockholm. Even if this is true, you have to allow for two factors: 1. The additional cost of getting from Stockholm back to Copenhagen for your flight back. This many include a night in a hotel. 2. The risk of a missed connection. If you fly an open-jaw ticket, even with a connection, the airline is responsible for getting you home if a connection is missed due to a late flight. But if you're using a separate ticket to get from Stockholm to Copenhagen (whether air or train) and you miss your flight out of Copenhagen, YOU are responsible for the cost. A one-way ticket from Copenhagen to California, bought at the last minute, will be thousands. That's why I talked of a night in a hotel above. If I were using separate tickets, I'd be too scared to train or fly from STO to CPH on the same day as my international flight (others would not mind this risk). If you wanted to spend an extra night in Copenhagen anyway, that's fine, but if you didn't, I'd book the open jaw (California to CPH, and STO to California).

While pretty cheap flights from Stockholm to Copenhagen can be had, I'm not sure how the total cost would be less than the difference flying open jaw. Though you could take the train and enjoy a few extra days or stops along the way back. Or rent a car to sightsee Sweden and drop it off in Malmo to avoid any foreign drop-off fees.

We did similar but started and finished in Copenhagen because the flight was cheaper and direct. If you're flying SAS, they offer a good deal to add Scandinavia area flights so you could take advantage of that. If not, I'd probably opt for a cheap flight - you will already have seen the archipeligo by sea - which is the primary reason for a ferry trip between the two. Trains in Scandinavia aren't cheap and the countryside in Sweden isn't really worth seeing. Before you fly back though, a side trip to Uppsala might be fun. It's a college town with tons of history that isn't on most people's tourist radar.