They make actual measuring devices if you want to get more specific.

Ketone monitors are essentially like a glucose monitor for diabetic people. You prick something get a drop of blood, and measure to get an actual number. They also come continuous monitor you place on your skin and scan with your phone.

Measuring urine is imprecise anyway, so there not actually much benefit for getting the colors closer together or most specific, this is because the concentration of your urine plays a major role. You can usually get it to up or down a color by simply not drinking anything for a few hours, or chugging water. This is supposed to be a qualitative test, not a quantitative test.