EC50 Calculator

What is EC50?

EC50 (half maximal effective concentration) is the concentration of a drug, antibody or toxicant which induces a response halfway between the baseline and maximum after a specified exposure time. It's commonly used as a measure of drug potency.

How to Use

1. Enter concentrations (usually log scale)
2. Enter response values (% inhibition or activity)
3. Add replicates for better accuracy
4. Click Calculate to fit the curve
5. View IC50 value and curve fit

Data Requirements

• At least 4 concentration points
• Include concentrations above and below EC50
• Use log-spaced concentrations
• Response values typically 0-100%
• Multiple replicates improve accuracy

Hill Slope Interpretation

• 1: Standard dose-response
• > 1: Steep curve (cooperative binding)
• < 1: Shallow curve (multiple sites)
• Negative: Inverse response

Applications

• Drug discovery and screening
• Enzyme inhibition studies
• Cell viability assays
• Receptor binding assays
• Toxicology studies

FAQ

Q: EC50 vs IC50?
A: EC50 measures activation/effect, IC50 measures inhibition.

Q: Why use log concentrations?
A: Log scale provides better curve fitting across wide concentration ranges.