u/Forza458

Hi all, I don't fly much so asking a noob question here.

Just flown from BNE to SG and had a max limit of 30kg for luggage. I put my bag on the bag drop-off scale and unfortunately, I had 31.2kg. Was ready for my bag to be rejected but it got checked in (with the heavy tag) and did not had to pay the excess fee.

Is there a certain unwritten threshold? I did checked in 3 hours early if that matters