How much liquid soap do you need in water to clean?

[aab1]

How much liquid soap would you need to put in say a gallon of water to be able to use that water to clean things with it?

Thanks

 

[LunaSkye]

I think it may depend on the concentration of the soap. When I spray cleaner, my personal rule of thumb is to use enough soap to make a few bubbles. When I mop, I use a bit more so I can see a light lather.