Assuming you're talking about grilling burgers at 400 degrees Fahrenheit:
It typically takes about 10-12 minutes to grill burgers at 400 degrees Fahrenheit. This cook time will produce a burger that is medium-rare in the center, with a slightly pink middle and well-done edges. If you like your burgers more well-done, simply cook them for a few minutes longer.
For the best results, use fresh ground beef that is 80/20 ground chuck. Form the patties by hand, and make sure they are all roughly the same thickness so they will cook evenly. Season the burgers with salt and pepper (or your favorite seasoning blend) just before grilling.
Place the burgers on a preheated grill over direct heat. Cook for 5-7 minutes per side, flipping only once during cooking. Avoid pressing down on the burgers while they are cooking, as this can cause them to become tough and dry out.
Once fully cooked, remove from grill and allow to rest for 3-5 minutes before serving on a bun with your favorite toppings.