Its easy no algebra required smoothie equation. Four to one, one part yogurt, one part milk, one part fruit, one banana. Did you notice anything missing like ice ? Here is a little secret. Use extra cold fruit of frozen banana for instance if you need the chill. Now place these things in your blender chopped up fruit, we strawberries then add yogurt and milk. Finish with a slice of banana. Blend and pulse your way to a smoothie consistency you like. Looking for a protein boost with your smoothie? Just toss in a scoop of whey powder, wheat germ or peanut butter to power up, now you have a delicious smoothie with a pack of protein.