Four of the five buses that depart Amsterdam Airport Schiphol for Antwerp every day run directly, making it possible to avoid travels that need changing.
These direct buses travel the 124 km journey in an average of 2 hours and 51 minutes, but if you schedule it properly, certain buses may get you there in as little as 2 hours and 25 minutes.
The slowest buses will take 3 h 10 m and normally entail a change or two along the route, but if you're on a tight budget, you might be able to save a few pence.