Search before using a remembered fare
Official inventory and the available train mix depend on the travel date. Use the KORAIL booking service to record the standard-class total per traveller. The calculator is intentionally based on that live basket because a static blog price can become inaccurate and create a false saving.
Include the complete onward plan
If Jeonju is followed by Busan, Gyeongju or another rail stop, add every eligible one-way ticket you would otherwise purchase. If you return to Seoul, include that ticket too. Do not include city taxis, buses or accommodation transfers in the rail comparison.
Let days, not enthusiasm, select the pass
A pass covers selected travel dates, not an unlimited number of holiday days. Keep the number of rail dates and one-way journeys honest, then read the reservation warning in the result. If individual tickets win, that is still a useful answer and avoids paying for unused pass capacity.