What is the difference between a full and a half bath in the resale value of a house?

Half-baths contain a toilet and a sink, but no bathtub or shower stall. The National Association of Home Buyers estimates that adding a half bath will add 10.5% to the value of a home and adding a full bath will add 20%. Depending on the value of your home, adding either may be more costly than what you will recoup when selling your home.