Calculate EC50/IC50 values and plot dose-response curves using 4-parameter logistic regression with hill slope analysis
EC50/IC50 Value
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Hill Slope
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R² Value
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Top (Max Response)
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Bottom (Min Response)
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EC50 is the concentration that produces 50% of the maximum effect, while IC50 is the concentration that produces 50% inhibition. EC50 is used for activation studies, IC50 for inhibition studies.
Enter concentration and response values separated by commas, one pair per line. You need at least 4-6 data points spanning above and below the expected EC50/IC50 value for accurate curve fitting.
The Hill slope indicates the steepness of the curve. A slope of 1 indicates a standard sigmoidal curve, while slopes >1 indicate cooperative binding and slopes <1 indicate negative cooperativity.
R² measures how well the 4-parameter logistic model fits your data, ranging from 0 to 1. Values above 0.95 indicate excellent fit, while values below 0.8 suggest poor curve fitting.
Logarithmic scale is recommended for most dose-response studies as it better displays the sigmoidal nature of the curve and is standard in pharmacology. Linear scale may be used for narrow concentration ranges.
The equation is: Y = Bottom + (Top - Bottom) / (1 + (X/EC50)^HillSlope). This models the sigmoidal dose-response relationship with four key parameters: top, bottom, EC50, and hill slope.
You need at least 4-6 concentration points, but 8-12 points provide better accuracy. Include concentrations both above and below your expected EC50 value, ideally spanning 2-3 orders of magnitude.
Yes, this calculator works for various assays including cell viability, enzyme inhibition, receptor binding, and drug efficacy studies. Simply select the appropriate response type and units.