How many milliliters are in 500 grams?

Milliliters (ml) are a measure of volume and grams (g) are a measure of weight, so there is no direct conversion except in the case of water, which weighs 1 gram per milliliter. Most cooking ingredients, however are fairly close to having a similar weight per volume as that of water, so it is usually fairly safe to use either grams or milliliters when measuring them.