What is the formula to get the BOD to COD Ratio?

The BOD to COD ratio is calculated using the formula:

[ \text{BOD to COD Ratio} = \frac{\text{BOD}_5}{\text{COD}} ]

where (\text{BOD}_5) is the biochemical oxygen demand measured over a 5-day period, and COD is the chemical oxygen demand. This ratio helps assess the proportion of biodegradable organic matter in wastewater; a higher ratio indicates a higher level of biodegradable material.