Does anyone know if a International Drivers Permit is required to drive in Belgium?

It is not.

No, it's not.

Okay, thanks J62 and StCirq. Am awaiting an answer from Europcar to see if they require one. I didn't need one in other countries I visited but seems like each country is different.

You can't judge the legal requirement based on whether or not the rental car co cares.

Even in countries that require an IDP (Italy, Austria) it's rare that rental car companies ask for one.

In Belgium, it's not a legal requirement, nor will Europcar ask to see one.

Whatever the rental car company says is entirely irrelevant. In countries where it's required, they may not even ask you for it. In countries where it isn't, they may tell you you need one. They have no clue most of the time. It's the legal authorities who care.

Italy requires it. Austria requires it. Belgium does not, no matter what anyone tells you

I understand that whatever the rental car people say is irrelevant as far as the law is concerned. However, I have heard of rental car companies not letting one rent if they DIDN"T have an IDP.
It's academic now. Just heard from Europcar and THEY do not require a IDP as a condition of rental for Belgium.