Why can you convert 1ml into 1cm3?

1 milliliter (ml) is equal to 1 cubic centimeter (cm³) because both units measure volume. The milliliter is defined as one-thousandth of a liter, while a cubic centimeter is the volume of a cube with sides of one centimeter, which is also equivalent to one-thousandth of a liter. Thus, the two units are interchangeable, making the conversion straightforward.