Enter your Maximum Velocity (Vmax), Substrate Concentration [S], and Michaelis Constant (Km) into the Michaelis-Menten Calculator to find the Reaction Velocity (v) — or flip it around to solve for any unknown variable. Along with your calculated value, you'll also see the Enzyme Saturation and [S]/Km Ratio to better understand where your enzyme stands on the saturation curve.
Calculated Value
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Enzyme Saturation
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[S]/Km Ratio
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Select what parameter you want to calculate (velocity, Vmax, substrate concentration, or Km), then enter the known values in the other fields. The calculator will solve for your chosen parameter using the Michaelis-Menten equation.
Km is the substrate concentration at which the reaction velocity equals half the maximum velocity (Vmax/2). It indicates the enzyme's affinity for its substrate - lower Km means higher affinity.
Vmax is the maximum reaction velocity achieved when the enzyme is saturated with substrate. At this point, all enzyme active sites are occupied and increasing substrate concentration won't increase the reaction rate further.
Enzyme saturation is calculated as v/Vmax × 100%, where v is the current reaction velocity. It shows what percentage of the maximum possible rate is being achieved at the current substrate concentration.
The [S]/Km ratio indicates the kinetic regime. When [S] << Km (ratio < 0.1), the reaction follows first-order kinetics. When [S] >> Km (ratio > 10), it follows zero-order kinetics and approaches saturation.
The equation applies to single-substrate enzyme reactions under steady-state conditions, assuming rapid equilibrium between enzyme and substrate. It's most accurate for simple enzymatic reactions without inhibition or cooperativity.
The curve shows how reaction velocity changes with substrate concentration. It starts linear at low [S], then curves and plateaus at Vmax. The Km value marks the substrate concentration at the curve's midpoint.