You may see people that have never lifted a weight in their lives and don't work out at all who have large calf muscles. By contrast, you may see athletes and weight trainers that don't have very developed lower legs. If you fall into the first category, you're lucky. You won't have to put very much effort nto training your calves. However, if you have naurally small calves, you must focus on doing calf exercises with a lot of intensity to get them to grow.
The are 2 main ways to do calf exercises - with the legs straight or bent at the knees. Straight legged calf exercises will work the gastrocnemius muscle. Doing exercises for the calves with the knees bent will work the soleus muscle that lies under the gastrocnemius.
The best calf exercises to do with the legs straight are standing calf raises and leg press calf raises.
Just about every gym has a machine that will allow you to do standing calf raises. You basically have to put your shoulders under the pads and raise the weight up and down using the calf muscles. As with any calf weight training exercise, you'll want to keep on your toes. Go down until you feel a nice stretch in your calves, then raise up until you are on your toes and you feel a hard contraction in the calf muscles. If you don't have access to a standing calf machine because you weight train at home, you can put a weight on your shoulders with your toes on a sturdy block and raise your heels to do calf raises.
You can mimic standing calf exercises by doing them on a leg press machine. The movement is basically the same, you lower the weight then lift it with your toes. When you're training your legs, you can do regular leg presses, rest for a minute, then do calf raises to save time at the gym.
For full calf development, you must do seted calf raises. This great calf exercise is usually done on a machine that allows you put your thighs under a pad and lift the weight using your toes. Once again, you'll want to get a full stretch and strong contraction. If you don't have access to a seated calf machine you can put a towel on your thighs while seated and put a weight on the towel.
Another calf exercise you can do is to put your heel on a block raise your toes up and down. This will target the fronts of the calves and have prevent shin splints.
If you run as part of your cardio routine, it will help you build bigger calves. Some shorter distance sprints and jogging in between them will definitely help you build the calf muscles.
The calves are a very dense muscle that needs a lot of work to grow. You are constantly using them while you walk, so you really have to hit them hard to get a response. When you do calf exercises, you should do mostly high rep sets with as much weight as possible. It may burn like crazy, but that's what you need to do to get them to grow. You can do some bouncing style reps after you've done as many full reps as possible to really burn out the calves. Drop sets are another great technique to use for these muscles. You can also do calf exercises more often than exercises for other muscle groups because they recover quickly.
Stick with your calf exercise routine and eventually you'll see the results you're looking for.