How many milligrams are in 3 Liters?

3000 mg water = 3g water = 0.003 kg water

Water Density is ----> 1000 kg/m3

One litre is equal to 1/1,000 cubic metre

1000 kg/m3 * 1/1000 m3 = 1 kg in 1/1000 cubic meter

Therefore if 1 kg is 1 liter, 0.003 kg is 0.003 liter.

"0.003 liters"