Typically, about a teaspoon of semen is released when a guy ejaculates. If he ejaculates often, the amount usually decreases. That's normal since it takes about five to seven days for a guy to produce enough semen for a full ejaculation. If he ejaculates often, he would not have had time to build up the supply, so less will come out. There will always be some fluid with sperm released; so remember, it only takes one sperm to fertilize an egg!