ELISA Calculator

Four Parameter Logistic (4PL) is the most common curve fitting method for ELISA assays. It produces an S-shaped curve that better fits the typical dose-response relationship in immunoassays, especially when dealing with high and low concentration ranges.

R² (coefficient of determination) indicates how well your standard curve fits the data points. Values closer to 1.0 indicate better fit. Generally, R² values above 0.95 are considered acceptable for ELISA assays, with values above 0.99 being excellent.

Enter your optical density values as they appear from your plate reader, typically in a 12x8 matrix format. Separate each value with a space or tab. You can copy and paste directly from Excel or Word documents.

For standards, duplicate or triplicate measurements are recommended to ensure accuracy of the standard curve. For samples, duplicates are typically sufficient, though triplicates provide better precision for critical measurements.

CV measures the variability between replicate measurements. For ELISA assays, CV values below 10% are generally acceptable for standards, while CV values below 15% are acceptable for samples.

The dilution factor depends on your analyte's concentration range. 1:2 serial dilutions provide more data points and better curve resolution, while 1:10 dilutions cover broader concentration ranges with fewer standards.

Poor curve fit can result from pipetting errors, expired reagents, or inappropriate dilution ranges. Check your standard preparation, ensure proper mixing, and consider using different curve fitting methods or adjusting your concentration range.

Yes, this calculator works for any assay that uses a standard curve approach, including chemiluminescent immunoassays, fluorescent assays, and other plate-based immunoassays that measure dose-response relationships.