Competitive Binding Calculator

Calculate Ki from IC50 using the Cheng-Prusoff equation for competitive binding

Competition Parameters

Radioligand Concentration [L*] (nM)

Radioligand Kd (nM)

Competitor IC50 (nM)

Competitor Concentration [I] (nM)

Bmax (fmol/mg)

Inhibition Constant (Ki)

16.6667 nM

pKi = 7.78

Apparent Kd

0.8000 nM

Fold Shift

1.60x

Without Competitor

66.67

With Competitor

55.56

Percent Inhibition

16.67%

Ki = IC50 / (1 + [L*]/Kd)

Valid for competitive inhibitors only

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MyCalcBuddy Editorial Team

This page is maintained as an educational calculator reference.

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Formula Source: Standard Mathematical References

by Various

ðŸ”„Last reviewed: May 2026

âœ“Formula checks are based on standard references and internal QA review.