Purely in weight conversion terms 300 grams is equivalent to 10.582 ounces, or if you prefer, .661 pounds or .047 stone.
If you want a something you can equate to then 300 grams works out to be about a quarter of a bag of sugar or small box of cereal.
If you want a something you can equate to then 300 grams works out to be about a quarter of a bag of sugar or small box of cereal.