Find my iPhone isn't working very good?

I got an iPad 2 a year ago and it's in mint condition and I also have an iPhone which I check it's whereabouts if I ever lose it. Whenever I go on find my iphone (on my iphone, ipad or computer) it always says my ipad is on the main road to the left of my house. (I'd say about 50 meters away).
I've never lost my ipad before and now I'm afraid that if I lose it, i won't find it because the Find My iPhone app is a little bit off (it works perfectly for my iphone 5).
So my question is, is there a way to calibrate it or anything? I've tried restarting it, refreshing the app, restoring it to factory settings but nothing works.
What do I do?