Hi Dacoda! I think we need a little more information to work out the true mass, though I can share with you that "mass = volume x density". Let's do the maths with Water, as with water 1 millilitre = 1 gram mass So in this case: volume = 1000ml density = 1g/ml mass = 1000 x 1 mass = 1000g Hope that helps, be sure to find out the density when approaching a question like this. Usually expressed as 'g/ml' which tells you how many 'grams per millilitre'.