For a standard main course portion, the culinary guideline is between 400 and 500 milliliters (about 1.5 to 2 cups) per person. When serving soup as the primary dish rather than a starter, people generally appreciate a generous bowl, especially if the soup is on the lighter side.
For six people, this calculation works out as follows:
If you are aiming for a moderate serving of 400 milliliters per person, you will need a total of 2.4 liters.
If you prefer a heartier serving of 500 milliliters per person, you will need a total of 3.0 liters.
In practical terms, preparing between 2.5 and 3.0 liters is the ideal target for a weeknight dinner. This ensures everyone gets a satisfying meal with a little extra room for second helpings or slight evaporation during cooking.