It depends on which country you're in, and its electrical circuits. Basically, a certain number of sockets will be connected to one circuit in your electricity box (the fuse and switch box, where the mains comes into your house and is connected up to the different sockets / lights / cookers etc. through fuses).
Some people above have given you the ratings for 120V US sockets. In the UK, it's 240V and up to about 3KW, so you can roughly scale these accordingly. BUT, bear in mind that the voltages are different and need conversion (see Ohms Law) and, don't forget to count anything on the same circuit that's already using power. For example, if you hook all this up and it runs at the maximum load, but then your tumble dryer switches on, on the same circuit, you'll be in trouble.