Career
He has previously played for the Norwegian Tippeligaen club Start and been contracted for two years to Huddersfield Town in the Football League Championship. Tronstad has represented his country at youth level Tronstad played for Tveit Illinois before he joined Start.
In November 2009 he was on a trial with Manchester United together with his countrymen Herman Stengel and Mats Møller Dæhli.
Tronstad made his first-team debut for Start in the First Division in 2012, and made his debut in Tippeligaen the following season. He has been compared to the former Start-player and Norway international, Fredrik Strømstad.
On 21 January 2014, Sondre joined Huddersfield Town on a 2 1⁄2-year deal. Tronstad has played for Norwegian youth teams from under-16 to under-18 level