A steak needs to rest for about five to seven minutes before you serve it. This has nothing to do with the steak being tired, and everything to do with wanting it to be as juicy as possible.
The Perfect Steak Is a Juicy Steak
If you were to cut into a steak straight from the grill, you’d see a huge pool of juices come spilling out all over your plate. But if you wait five minutes or so before cutting into it, you won’t see that.
A useful guideline for resting a steak is to let it rest for approximately as long as you cooked it. Another guideline is to let it rest for five minutes for every inch of thickness. (The perfect steak is 1½ inches thick.) Some cooks talk about resting meats 10 minutes for each pound of meat. As you can see, all of these guidelines are basically saying the same thing. Rest your steak for five to seven minutes before slicing it.
One way to rest steaks is to take them off the grill, transfer them to a cutting board and then tent them under a big piece of foil. You can then use these five to seven minutes to prepare a sauce, make up a salad, get your baked potatoes ready, set the table or whatever.