What is the Michaelis-Menten equation?

It is v = Vmax × [S] / (Km + [S]), where v is the initial reaction velocity at substrate concentration [S], Vmax is the maximum velocity (enzyme fully saturated), and Km is the substrate concentration at which v = ½Vmax.

What is the Lineweaver-Burk plot?

The Lineweaver-Burk plot graphs 1/v on the y-axis against 1/[S] on the x-axis, transforming the hyperbolic Michaelis-Menten curve into a straight line. The y-intercept equals 1/Vmax and the x-intercept equals −1/Km, making it easy to determine both constants from experimental data.

What does a low Km mean?

A low Km means the enzyme reaches half-maximal velocity at a low substrate concentration, indicating high affinity between the enzyme and its substrate. A high Km indicates lower affinity and requires more substrate to achieve the same velocity.

What units should I use?

The calculator is unit-agnostic. Vmax and the result v share the same velocity unit (e.g., µmol/min, nmol/s). Km and [S] must share the same concentration unit (e.g., µM, mM). Enter consistent units and the math is correct regardless of scale.

How does competitive inhibition change the parameters?

A competitive inhibitor increases the apparent Km (lowers apparent affinity) but leaves Vmax unchanged, because high [S] can outcompete the inhibitor. On a Lineweaver-Burk plot, competitive inhibition rotates the line around the y-intercept (same 1/Vmax, different slope).

How does non-competitive inhibition change the parameters?

A non-competitive inhibitor reduces the apparent Vmax without changing Km, because the inhibitor binds a site other than the active site and cannot be outcompeted by substrate. On a Lineweaver-Burk plot, the lines intersect on the x-axis (same −1/Km, different y-intercept).

Michaelis-Menten Calculator

Enter Vmax, Km, and substrate concentration to instantly calculate reaction velocity, saturation percentage, and view the Lineweaver-Burk double-reciprocal plot.

Kinetic Parameters

V_max — Maximum velocity

Reaction rate when enzyme is fully saturated with substrate.

K_m — Michaelis constant

[S] at which v = ½ V_max. Lower Km = higher enzyme-substrate affinity.

[S] — Substrate concentration

Must use the same unit as K_m.

Result

Reaction velocity (v)

—

% of V_max

—

saturation level

0 ½V_max @ K_m V_max

v = V_max × [S] / (K_m + [S])
v = — × — / (— + —)
v = —

V_max —

½ V_max (at K_m) —

K_m —

[S] for 90% V_max —

Summary

The Michaelis-Menten Calculator applies the fundamental enzyme kinetics equation v = Vmax × [S] / (Km + [S]) to compute reaction velocity for any substrate concentration. Enter your Vmax (maximum velocity), Km (Michaelis constant), and [S] (substrate concentration) to get the exact reaction rate, its percentage of Vmax, and a step-by-step formula breakdown. The tool also renders a Lineweaver-Burk double-reciprocal plot (1/v vs 1/[S]), which is widely used to determine Vmax and Km from experimental data.

How it works

Enter the maximum velocity Vmax — the rate when all enzyme active sites are saturated.
Enter Km — the substrate concentration at which v equals half of Vmax.
Enter [S] — the substrate concentration at which you want the reaction velocity.
Click Calculate; the tool applies v = Vmax × [S] / (Km + [S]) and displays the result.
The saturation bar shows what fraction of Vmax has been reached.
Switch to the Lineweaver-Burk tab to see the double-reciprocal linear transformation of the curve.

Use cases

Compute the reaction velocity of an enzyme at a specific substrate concentration.
Verify that an experimentally measured velocity matches the Michaelis-Menten model.
Visualize enzyme saturation using the Lineweaver-Burk double-reciprocal plot.
Determine Km and Vmax graphically from linearized experimental data.
Compare enzyme efficiency by exploring how different Km values shift the curve.
Teach enzyme kinetics concepts with an interactive formula demonstration.
Estimate how much substrate is needed to achieve 90% or 95% of Vmax.
Analyze competitive vs. non-competitive inhibition by adjusting Km or Vmax.

Frequently Asked Questions

Last updated: 2026-09-30 · Reviewed by Nham Vu