Not an easy question to answer because of all the variables. Its one thing if you have one person surfing the net and its another thing if mom is watching NetFlix, Junior is in the basement playing Xbox on the net, daughter is playing a video on her smartphone up in her room, and dad is VPN'ed into work. And then you have RF issues from your neighbor's routers and then everyone in the neighborhood has the same profile as above and we're all trying to cram gigabytes of throughput over the same pipe.
I suggest reading: http://www.pcmag.com/article2/0,2817,2347539,00.asp
(and links off of it) to get a handle on all the variables at play.
A friend of mine sent me this link and I thought it was interesting http://www.smallnetbuilder.com/wirel...x-bad-wireless