A measuring jug or cup is the best way to measure liquid. Place the jug on a flat surface and make sure that you are looking at it at eye level. Can you see the two hundred millilitre line?

Estimate how much liquid is left in each container. If possible, use a measuring jug for each to check your estimates.

This means I can hide the jug under a table where floor space ... but double-checking the water amount with a liquid measuring cup is always a good idea. I don't recommend using it with dry ...