I'll be flying into Brussels in May, mainly because I can't easily fly into Bruges, and want to immediately take the train to Bruges (yes, I know I'm missing plenty by only going to Bruges, but I only have so many days and want to return to Paris after Bruges). Looks as though the airport has a train station. My questions are:
Do I have to worry about the trains being full? I'd rather not book it ahead in case my flight is delayed.
How far is it from baggage pick-up (I probably will be checking a bag) to the train?
Thanks!

I am assuming you are flying into Zaventem and not Charleroi. No, you don't have to worry about trains being full (just jump on the next one). Trains are all mass transit and you can't book a seat. There is no special advantage to buying early (apart from your comfort), and a ticket allows you to catch any train. The only thing you need to be aware of is that there is an airport supplement ticket, the Diabolo, which must be purchased as well. There are ticket machines that can offer English, and a ticket window with a human, so don't worry about this. There is also an app that you can use to buy tickets (SNCB/NMBS).

The train station is two floors below the arrivals floor (floor -1), it's part of the same complex. There will be a stream of people all going to do the same thing as you, so just go along with them until you have to choose your train.

There are also a bunch of videos about buying your train ticket from Zaventem on YouTube. I haven't linked to one of them but just google "buying train ticket from Brussels Airport" and a whole lot should come up, showing you what the machines look like.

Lavandula

Thank you, lavandula. This is just what I was looking for! I'm not worried about actually buying the ticket, but it's good to know about the Diabolo, so thanks.

Oh, also there is a gate that scans the barcode on your ticket so have it ready to enter the train area. Glad you will find your feet, enjoy your trip.

Lavandula

SusanP, we too flew to Brussels few years ago and immediately jumped on the train to Bruges where we spent 4-5 nights -- so glad we did, liked it much more than we did Brussels and Ghent, and then returned thru Brussels to go to Paris Gare du Nord. We didnt pre-buy tix either, it seems very easy. Lavandula was a good source of info.

Thanks, lavandula, I'll add that to my notes.

Alice, glad to know it's easy.

Last year when I was in Belgium there was some talk about being able to tap in / tap out with a credit card or smart phone, without even needing to buy a ticket. I was able to do that in the Netherlands, but not sure if it has been rolled out in Belgium yet.

It is possible for public transport (metro, tram, buses) in Brussels (STIB/MIVB) (and Flanders???? not sure), but not possible on the trains (SNCB/NMBS), unlike in the Netherlands.

Lavandula