So, just how long should you grill hamburgers? Well, that depends on two things: how you like your hamburgers done and how thick your patties are.
Let's start with the patties...
The optimal thickness for burgers is about 3/4 of an inch thick (unless your making sliders or mini's which can be made a little thinner). Any thinner than they can tear when you transfer them onto the grill and dry out while being grilled. Any thicker and you risk ending up with a burger that's either done on the outside but raw in the middle or charred on the outside and and done in the middle.
As for the optimal doneness, well, that's up to you. The FDA recommends nothing short of well done, warning that "Consuming raw or undercooked meats or poultry may result in food-borne illness."
However, while we wholeheartedly agree with that recommendation when it comes to burgers made out of poulty, pigs will fly before we give up succulent pink, juicy, medium-rare middles in our beef burgers!
That said, here are average grilling times for burgers when grilling with the tried-and-true method of direct, high heat (450-650° F):
Medium Rare (130-135° F): Grill for 3 minutes, flip, grill for 4 more minutes.
Medium (135-150° F): Grill for 3 minutes, flip, grill for 5 more minutes.
Medium Well (150-165° F): Grill for 3 minutes, flip, grill for 6 more minutes.
Well Done (165° F and up): Grill for 3 minutes, flip, grill for 7 more minutes.
Turkey or chicken burgers:
Well: Grill for 5 minutes, flip, grill for 5 more minutes. (170° F)
However, keep in mind that time alone is never a reliable measure of doneness. There are just to many things that can affect it (patty thickness, wind, outdoor temp., heat source consistency, and so on...). The only 100% failsafe, spot-on way to know if you burger is really done is with an instant-read thermometer.
So, select the doneness that sets your mouth a watering. Toss your burgers on the grill. Then, when the time for that doneness is almost up, insert the thermometer to see if your burgers are ready.