Arlanda Express is bit more expensive but very quick train which only takes 20 minutes to reach the city Central Station and departs from terminal 2. Arlanda Express departs after every 10–15 minutes whole day, free Wi-Fi is available on the train. 

Buy tickets from Kiosks at the platform or on-line; you can also buy from the ticket machines at Arlanda airport. 

Weekend discounts are available on buying return tickets online. 

Price: 

Adults 260 SEK one way 490 SEK return Youth & Seniors Almost Half the price (from 18–25 & plus 65 years) Website : https://www.arlandaexpress.com/