I thought I should cover this as it can be a difficult, emotional process. But really, it is quite simple:
Only invite people that you want there.
I say this is simple and I believe in most cases it can be this straight forward. There are all sorts of etiquette that you ‘should’ keep to as with other stages of wedding planning. But in the end, if you ever feel obliged to invite someone then don’t do it. Great uncle Fred who you’ve not seen for 15 years doesn’t need to be invited even though you went to his daughters wedding when you were 5. This is not a time for your parents to start repaying family favors of past weddings and social invites. Be aware of this happening sometimes.
You also have to consider your budget, if you want 250 people and you can’t afford a three course meal for all of them then I would look at amending your catering so that you can afford it. Maybe you will have a big party and a type of buffet dinner?
You have to keep things realistic, your venue could limit your guest list too and in a way this can be a blessing. Sometimes less is more.
When you look out at your guests on the day the most important thing to see is a room full of people you love and who have been a part of your life and who you want to share this very intimate, special day with.
Great uncle Fred will understand.