4PL ELISA Curve Fitter
Paste assay data, fit a 4-parameter logistic curve, batch-calculate unknowns. Everything stays in your browser.
1. Data Entry
Paste tab/comma/space-separated data. Column 1 = X (concentration), columns 2+ = Y replicates (OD). One row per X value. Straight from Excel.
2. Parsed Data Verification
3. Fit Results
A
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Min (bottom asymptote)
D
—
Max (top asymptote)
C
—
EC50 / IC50 (inflection)
B
—
Hill slope
Fitted equation (symbolic):
Y = D + (A − D) / (1 + (X / C)^B)
where A = min, D = max, C = EC50, B = Hill slope
Y = D + (A − D) / (1 + (X / C)^B)
where A = min, D = max, C = EC50, B = Hill slope
With fitted values:
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Cite this tool:
4. Batch Calculator
Paste a column of values. Get a column of results back. Ready to paste into Excel.
Results will appear here...