Enzyme Activity Calculator

Work out enzyme activity instantly with clear inputs, formula shown and shareable results.

About Enzyme Activity Calculator

Defines one unit as one micromole of product per minute and divides by protein mass to give specific activity.

Formula

Enzyme units

1 U = 1 micromol of product per minute; specific activity = U / mg protein; 1 katal = 1 mol/s, so 1 U = 16.67 nkat

Worked example

With the default values below, Enzyme Activity Calculator returns Enzyme activity of 1.50000. Change any input above and every figure here is recalculated in your browser.

Inputs used

Product formedaccepts 0–10,000 micromol: 4.5 micromol
Reaction timeaccepts 0.01–600 min: 3 min
Protein in the assayaccepts 0–1,000 mg: 0.5 mg

Results

Enzyme activity: 1.50000 U
Specific activity: 3.00000 U/mg
Activity: 0.000000025000 kat
Product formed per hour: 90.0000 micromol/h

Step by step

1Values used
2Enzyme units
3Enzyme activity= 1.50000 U
4Specific activity= 3.00000 U/mg
5Activity= 0.000000025000 kat
6Product formed per hour= 90.0000 micromol/h

Assumptions and limits

The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 12 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

Why measure specific activity?

It tracks purification: total units fall while specific activity rises as contaminating protein is removed.

Must the rate be initial?

Yes. Activity is defined from the initial linear phase before substrate depletion or product inhibition.