Venue size help

Can you get a floorplan and then make a layout of how everything will fit?

Ask the venue to show a floor plan of how it would be set up for maximum capacity.

The website AllSeated I've found to be really helpful. They may already have a floor plan for your venue, or you can easily create one and add everything you plan to add at your wedding.

Usually the venues are open and honest about how many people they can fit, because there's logistics and codes they need to follow or they could get in trouble.

Like others have said, get a floor plan for how it'll be set up. Look at pictures from other events. Read reviews, all what other PPs have said.

While it is the venue's job to "sell the place", their maximum seating number exists for a reason, lol. If you know for a fact that the venue is indeed big enough, I would walk through the logistics of the seating, the measurements, etc. with FH and explain how it will work. If there is a shadow of doubt in your mind, and you think you may have more than 150 guests, do not book the venue. Not only is this rude to the venue owners, it's rude to your guests if there isn't enough seating/space for you to properly host them.

I don't think they'd lie to you about how many people the place holds. Yeah they want you to book and they want your money, but they could also be in a lot of trouble if they have more people than they can hold. (Fire hazards and stuff)

ETA: A legit place wouldn't lie about this at least

You mention it is an old mansion...Is the square footage and space for available seating all in one room, or is it multiple rooms? That may be why it will hold 150...because the assumption is multiple rooms will be used.

We looked at an old mansion for my daughter's wedding in MD, and even though there were multiple rooms that would be used for the cocktail hour and the buffet set up, there was a large glass solarium that had been added on to provide the 'single' space for all the tables and dancing at the reception.