If I added a bathroom before I sold it.. how much does that typically increase the value of my house by?

I’m looking at buying a potential house hack soon that is 7 bedrooms and 4 bathrooms.

So I guess it is win win for everyone.In this condition, if you are ADU enthutiast, you could either wait and see when and if ADU price and valuation would be adjusted so it's more profitable if it's being built.There's alternative though, like container house is only selling 40-50k that includes bathroom.

Due to a lack of space on the 2nd floor, there was not adequate space to add a 2nd bathroom so that I could have a master suite.

Bathrooms are the most expensive rooms to add.  

There is plenty of room next to the original bathroom to make a second full bath off the master bedroom turning it into a very nice master suite. 

This property even had carpet in the bathrooms (cheap builders)

You provide face masks, a bathroom and water.

I am looking in 2 different neighborhoods where the ARV for neighborhood 1 is $600K and neighborhood 2 is $1M (2 "identical" houses (3BR 2BA 2000SF) that need the "same amount of work" (Paint, floors, windows, both bathrooms and a kitchen).  

Basically a 3 bedroom apartment not sized proportionately. 3 bedrooms, 1 bathroom and small kitchen/living room.