Clan Medals are calculated using the following method.

<Clan Medal Calculation Method>
- Medals of Clan Members(Ratio varies upon the medal rank) + Total Clan Activity Score(Clan card support + World Battle victory score)

The ratio is different because top clan members play the most important role.
If there are top 10 clan members with high medals, the clan will still have high Clan Medals even if some members have low medals.