Each fluid ounce is equivalent to approximately 30 milliliters.
Thus, 4 fluid ounces will be equivalent to 4 times 30 milliliters:
4 fluid ounces ≅ 4 * 30 mililiters = 120 mililiters
To better understand, we can write the proportions:
fl. oz. mL
1 30
4 x
Cross multiplying, we obtain:
1x = 4*30
x = 120 (milliliters)