How to convert micrograms per milliliter to grams per liter [µg/ml to g/l]:. ρ g/l = × ρ µg/ml. How many grams per liter in a microgram per milliliter: If ρ µg/ml = 1 then ρ g/l = × 1 = g/l. How many grams per liter in 51 micrograms per milliliter: If ρ µg/ml = 51 then ρ g/l = × 51 = g/l. Note: Microgram per milliliter is a metric unit of density.