router range depends on many factors like construction material,design of the house,presence of glass windows etc.same router which works perfectly in one house will work poorly in another house of same area but with different construction materials/design.only thing you can do is either test an average router in your house to get some idea or buy the costliest router possible in your budget(for under 6000 i suggest tp-link or asus preferably with detachable antennas so you can have the option of replacing antenna with more powerful one to increase range if need arise).