Rent price relative to owning?

[Peter Burnside]

Is there a logic to pricing rent relative to the cost of paying a mortgage on the property if someone were to buy it at today's rates?

Ex. my current properties rent for about 112% of what someone would pay in a mortgage payment with 20% down if they bought the property now. (of course, my payment is much lower than someone would pay now, because I've held these a while)  Just wondering if anyone uses a rule like this in determining rent (in an area where there are few comps).