When it comes to determining how much soap to use in the dishwasher, it can be easy to just fill the soap dispenser to the brim and call it good. But we’ve got news for you: You may very well be using too much soap! You might also not be using enough soap, but this is far less likely as modern dishwashers generally have much better water efficiency than older models.
Using too much dishwasher detergent can leave behind residue that clogs your drain and allows mildew to grow. It can also leave deposits on your dishes that make them look cloudy and stained. You can save yourself a bit of money and improve dishwasher performance though by following these simple guidelines
How Much Soap to Use in the Dishwasher
The first thing to do when figuring how much soap to use in the dishwasher is to determine the hardness/softness of your water supply. There are handy DIY kits you can use to test this yourself (if you don’t already know). Another option is to ask your local water department.

The general rule is that the softer the water, the less soap that you have to use.
Once you’ve determined your water type, read the manufacturer’s instructions in regards to how much soap you should use.
If you have soft water, start out by trying to use about 25% less than the instructions suggest. Vice versa for hard water (use 25% more). If you’re pleased with the results, great! If not, a bit of trial and error can help determine what works best.
Pro Tip: Use Finish Tablets
On a side note, consider trying Finish dishwasher tablets and Jet Dry rinse aid. Dishwasher tablets eliminate measuring altogether, ensuring you’re using an appropriate amount.