Group chats on Telegram can now have up to 30,000 members. Admins can use advanced permissions and butler bots to keep the peace.
— Telegram Messenger (@telegram) October 23, 2017
根據這篇推文，2017/10/23號 群組調整為3萬人
紀錄一下之前的人數調整情況
我的文章 2017/09/11 調整為2萬人
官方Twitter也有提到上調到2萬的人訊息
Some group chats on Telegram hit the 10K members limit, so we've increased the maximum group size to 20K. Keep tesing our limits!
— Telegram Messenger (@telegram) September 11, 2017