Enter the doses
X: log(concentration), or concentrations with “X values are concentrations” ticked. Y: responses, replicates side by side.
WAVESPEED AI IC50 CALCULATOR YOUR DATA STAYS ON YOUR DEVICE
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Free IC50 & EC50 CalculatorDose–response curve fitting with confidence intervals.
Paste concentrations (or log concentrations) and responses with replicates: the four-parameter logistic fit gives Bottom, Top, Hill slope and the IC50/EC50 with its 95% confidence interval.
Compare compounds side by side and save the dose–response graph for your report.
IC50 with 95% CI4PL and 5PLNo upload
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THREE SIMPLE STEPS
How to use the IC50 Calculator
Fit the curve
The 4-parameter logistic is chosen; switch to 5 parameters for asymmetric curves, or fix Bottom and Top.
Read the IC50
The IC50/EC50 and its confidence interval, the Hill slope, R² and the curve on a log axis.
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IC50 Calculator FAQ
IC50 or EC50?
The same calculation: the concentration giving a response halfway between Bottom and Top. Call it IC50 for inhibition and EC50 for stimulation.
Should I normalise to 0–100%?
Not required. If your controls define 0% and 100%, you can fix Bottom = 0 and Top = 100 under Constraints.
Why is the confidence interval wide?
Usually because the plateaus are not reached by the tested doses. Add doses at both ends or fix a plateau you know.
Is my data uploaded?
No. The fit runs in your browser.
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IC50 with 95% CI · 4PL and 5PL · No upload