Assuming One Piece Ships are fast, let's say faster than Real Life Old Ships
I'd say they travel 200-250 KM a Day
I think SHs traveled for around 10 Months Pre-TS
And 5 Months Post-TS so far
So approximately SHs traveled around 100 Thousand KMs
Which is the Equivalent of going around the Earth twice & half
So overall, One Piece World seem to be Three times Bigger than ours
Just an Estimation