Transfer time for t1 to t3 at Beijing Airport

Could you tell me which type of your transfer?
Is it domestic to domestic, domestic to international, or international to domestic? The minimum transfer time of DD is 120 mins. The rest of two types need 160 mins.

Suppose you have enough time for transfer, there are free shuttle buses between T1 to T3.You can take that at No.7 Gate, Arrival Hall, T1. It's easy to find. If not, you may have to change to another flight.