i want to convert this as i am buying toothpaste by the gram and want to convert it to millilitre
Gram is a unit of weight.

Liter is a unit of volume.

Like apples and oranges.
surely toothpaste is sold in ml on the box/tube. Go to a recipe site , most have conversion tables
1ml = 1cm^3 You would have to find the volume of whatever weighed #g, (probably in cm^3), then convert to ml. There is no direct conversion between the two (that I know of). You could put the obj in a graduated cylinder with some water in it, then measure the water level before and after the item is inserted. the difference is its volume (in ml)
The reason that you are having trouble finding a conversion is that grams and milliliters measure different things. A gram is a unit of weight and a milliliter is a unit of volume. To convert one to the other you need to know what substance you are measuring. If you are measuring water then one milliliter weighs approximately one gram. If you are measuring mercury then one milliliter weighs approximately 13.59 grams.

Good Luck!
First, some definitions:
Volume is measured in litres (l) and is a measure of how much a a fluid is present in a liquid. Mass is a measure of how many particles there are in a particular object in physical terms. it is measured in Grams (g). Weight is the effect that a gravitational field has on an object. It is equal to the Mass times the gravitational field strength.

Due to this, you cannot simply convert Ml into g. However there are other ways to find your answer.

1) Squeeze all the toothpaste into a measuring jug and find out.
2) Measure out 1g of toothpast into a measuring jug, and multiply by 160
3) Take it as it is.
Let us calculate this

990gms=1ltr. and 1ltr.=1000ml




so 160gms=161.617ml. (Approx.)
multiply by 100