Most books will say use one cup of flour for each egg. My experience has been less rather than more flour is safer. I would use about 9/10ths a cup of flour to an egg. The goal is to make dough that has barely enough flour to absorb egg. There is no precise way to determine when this point has been reached. Variables such as the quality and size of the egg, flour, atmospheric conditions (e.g. humidity/time of year), make this an interesting challenge and fun. It becomes a matter of feel to determine if you are getting a good batch of dough, or one you should scrap and start over again. Sometimes, if you add a bit too much flour, you can salvage the dough by adding a few sprinkles of olive oil, water or wine. In fact, some people add one or more of these items as a matter of course, assuming it adds a little flavor or elasticity to the dough. I have tried them all and haven’t found any significant differences.
Be sure you use unbleached flour. I have found King Arthur’s the est. One time at my brother’s house, they slipped me some bleached flour and the dough was a catastrophe. If you plan to make spaghetti or fettuccine, it is a good idea to add some semolina flour to the unbleached flour. The more semolina you add, the more difficult it is to knead the dough. I have tried all sorts of ratios. I never use more than ⅓ semolina to ⅔ white. Less is better. The semolina gives the dough strength and makes the pasta a little more chewy.
The rule of thumb in determining how much pasta to make is one egg per person. However, four eggs will really take care of five people, and eight eggs could handle ten to twelve people. I generally make dough in batches of four eggs so if I want a lot of pasta, I do two batches. Four batches would pretty much take care of the Boston marathon crowd. By limiting yourself to four eggs per batch, it makes handling and kneading easier. Don’t forget to add a pinch of salt to each batch.
If you have a food processor it makes the initial blending of egg and flour much easier. If you use semolina, I would mix one cup with three cups flour and the pinch of salt first. Put the effs in the processor first, then gradually add the mixed flour until the dough balls up. Press your finger against the dough, if it is not too sticky, put it on a floured wooden surface and finish adding flour and kneading until the dough becomes pliable and shiny. Cover it with a towel and let rest for 15–20 minutes.
If you do not have a food processor, make a well of the floor on the wooden surface. Put the eggs in the well and beat them with a fork, scooping small portions of flour from the inside wall of the well to incorporate it with the eggs. This gets a bit messy, but eventually the eggs will absorb all the flour they can, and the dough will be ready got the 15 minute rest mentioned above. Use the resting time to clean your hands and the surface you have been working on.