Grams per milliliter to milligrams per liter conversion calculator shown above calculates how many milligrams per liter are in 'X' grams per milliliter (where 'X' is the number of grams per milliliter to convert to milligrams per liter). In order to convert a value from grams per milliliter to milligrams per liter (from g/mL to mg/L) simply type the number of g/mL to be converted to mg/L and then click on the 'convert' button.