Does it have an exterior exit door? If so, go for it.

Take some measurements and post a pic of a drawing (to scale ... graph paper) showing where the doors and windows are and the pros (and others of us) could probably help you with ideas for creating the change.

Do you already have a hall tree or bench or free standing at rack or wall hanging rack-- what are you contemplating putting in the mud room?

Updated post with a picture and room dimensions.

Go for it. I eliminated a half bath in my former home, also going from 3.5 to 3.0 baths. Never regretted it. We did leave the plumbing stubbed so someone in future could convert back. We did great on resale- I’m sure it didn’t hurt the price at all.

If it works for your current lifestyle, why not?

All the plumbing would still be in place so if anyone wanted to convert it back, it would be relatively easy to install a new sink and toilet.

How are the other bathrooms used? I like a powder room if other bathrooms are used as bathrooms to service bedrooms because that way the bathrooms don't have to be kept in shape for guests constantly. I think most people prefer to have "private" bathrooms and if the kids are using one of the bathrooms, they might not always be guest ready.

Would you consider keeping a sink/mirror if you converted it? Might be nice to have to wash hands upon coming indoors or a quick mirror check before walking out?

I also agree that if the 2 bathrooms on main floor are private bathrooms (master and hall?) then the hall bath will need to stay somewhat tidy. Not a huge deal (harder if you have very young children), but something to consider.

It's a great location for a mudroom. Nuke the door, add a bench and other storage.

You have another powder room somewhere?

The hall bath is a full bath and would be readily accessible for guests. We are empty nesters so keeping the bathroom clean is no problem!

I’ve wondered about the door but I think it has to stay; otherwise the hinges and such would leave unsightly holes. Our house is only 2 years old and I’m regretting doing the powder room instead of a mudroom.

Filling hinge mortises is easy peazy. The mudroom should be open. Consider deleting the partial walls as well. Make it totally open. Every time you and others enter from garage you will love it.

It's a great selling feature, too.

Don't be hesitant to get rid of the door. It's simple and straightforward to remove what's called the stop moulding and fill the mortises and screw holes for the hinges and strike plate. Once you repaint trim, it will be a regular cased doorway (a cased opening is a doorway that's trimmed out but does not contain a door).

You would never know that a door had been hung in the opening.

Sounds like a good idea to me, if you and your partner would actually use it. Is in a direct line from the garage entry into the house? If my DH had to deviate from a direct route to hang up his jacket, he wouldn’t do it. 🤬 Maybe yours is better trained than mine . . .

IMO if you want the space to be mud room then open it up

I agree with Little Bug that if you have to actually go into the mud room to use it, no one will (at least no one in my family would).

I'm not a pro but can we see the rest of the space? I am assuming the door in your picture is the one that leads to the garage. I think it would work best if the area is one big space (which means removing the door) than treating it as a separate room.

I have a mudroom in a closet about that size right next to the garage. I agree that nobody in my house deviates from direct route and it does not get used. It's like a dumping ground. I thought Oh cool I can shut the door when people come over but that doesn't happen either. I wish it was more open concept. I'd keep the bathroom lol.

I would be hesitant to give up a half bath for resale value. Is there not a closet you can use? I’m just not sure why empty nesters need a mud room.

That would not be a first choice. I would never give up a powder room, as that does lower the value of the home. Mud rooms that get used are “walk through”, not separate rooms that you have to go into. Those get things dropped at the door in a giant pile.

Perhaps you should post a measured plan of the home for other suggestions.