LC50 Calculator

Calculate median lethal concentration from toxicity data - the concentration causing mortality in 50% of test organisms

Enter Dose-Response Data

Concentration (mg/L)Mortality 1 (%)Mortality 2 (%)Mortality 3 (%)MeanAction
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What is LC50?

LC50 (median lethal concentration) is the concentration of a substance in water or air that causes death in 50% of test organisms. It's a standard measure for aquatic and airborne toxicity assessment.

How to Use

  1. Enter concentrations (mg/L or ppm)
  2. Enter mortality percentages
  3. Add replicates for better accuracy
  4. Click Calculate to fit the curve
  5. View LC50 value and curve fit

Data Requirements

  • At least 4 concentration points
  • Include concentrations above and below LC50
  • Use log-spaced concentrations
  • Mortality values 0-100%
  • Multiple replicates improve accuracy

Hill Slope Interpretation

  • 1: Standard dose-response
  • < -1: Steep curve (cooperative binding)
  • > -1: Shallow curve (multiple sites)
  • Positive: Inverse agonist or stimulation

Applications

  • Aquatic toxicology studies
  • Water quality assessment
  • Environmental impact evaluation
  • Fish and invertebrate testing
  • Regulatory compliance testing

FAQ

Q: How is LC50 expressed?
A: Usually in mg/L for water or mg/m³ for air, indicating the concentration in the exposure medium.

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