Use this chemistry calculator to reproduce a named relationship with explicit quantities and units for study, laboratory planning, or an independent numerical check.

IC50

Required number input.

[S]

Required number input.

Km

Required number input.

Compute Ki from IC50 via Cheng-Prusoff Ki = IC50/(1+S/Km). The tool evaluates the supplied inputs together and returns the named outputs below; it does not infer omitted operating conditions or change the units shown.^[1]

Ki

The resulting ki returned as a number.

• Compact enzyme-kinetic equations generally assume a defined mechanism, initial-rate conditions, stable enzyme concentration, and negligible substrate depletion. Cooperativity, inhibition type, transport, and assay artifacts can invalidate those assumptions.
• Use finite inputs in the displayed units and preserve more precision than the final presentation requires. Independently verify safety-critical, financial, compliance, or production decisions.

Check units and significant figures, compare the result with limiting cases, and use measured or source-specific constants where available. Laboratory, safety, and regulatory decisions require validated methods and appropriate uncertainty analysis.

• IC50 to Ki Converter

  Convert IC50 to Ki using Cheng-Prusoff equation Ki = IC50/(1+[S]/Km).

• Arrhenius Rate Constant

  Compute the Arrhenius rate constant as the frequency factor times exp of minus activation energy over R times temperature.

• BET Monolayer Capacity

  Derive BET monolayer capacity and BET C constant from the slope and intercept of a correctly prepared BET linear plot. Both must be positive for this form; choosing a valid relative-pressure range remains the analyst's responsibility.