From the graph find the maximum velocity and half it i.e. Vmax/2. Draw a horizontal line from this point till you find the point on the graph that corresponds to it and read off the substrate concentration at that point. This will give the value of Km.

How do you calculate Km value?

From the graph find the maximum velocity and half it i.e. Vmax/2. Draw a horizontal line from this point till you find the point on the graph that corresponds to it and read off the substrate concentration at that point. This will give the value of Km.

What is Km value?

Km value is equal to the substrate concentration at which half of the enzyme active sites are saturated with the substrate. It tells about the affinity of enzymes for their substrate. Km is the concentration of substrate at which half of the Vmax is attained.