YSK that in most modern washing machines, you only need 30 ml/1 ounce of detergent in a full load Why YSK: Half loads only need half that or less. And using more soap than that will often cause white spots on your clothes and can severely shorten your washer's lifespan. Detergent companies don't tell you that because they just want to sell you soap. Get a little medicine cup that would come with your Pepto or Nyquil and use that for your laundry soap instead of the big cup that comes with the container. Seeing white spots on your clothes? It's likely not the washer. Use less soap.