# BCA Assay Calculator (Protein Standard Curve) Least-squares A562 curve fit, back-calculated unknowns with dilution factor, extrapolation flags, and detergent/reducing-agent compatibility notes. Educational use only. > Canonical page: https://elysiatools.com/en/tools/bca-assay-calculator - **Category:** Education - **Keywords:** bca assay calculator, protein quantification a562, bicinchoninic acid assay, bca protein assay standard curve, protein concentration from absorbance, bca compatible detergents, dtt interference bca, microplate bca assay, unknown sample protein concentration, biochemistry calculator, lab calculator ## Overview The BCA Assay Calculator fits a least-squares protein standard curve from concentration and A562 readings, then back-calculates unknown protein concentrations using the sample dilution factor. It reports µg/mL and mg/mL results, fit statistics, and extrapolation flags for educational use. ## Inputs - **Protein Standards (µg/mL, A562)** (textarea): One standard per line: concentration in µg/mL, then A562 (comma, semicolon, tab, or space separated). - **Unknown Absorbances (A562)** (textarea): One sample A562 reading per line. - **Sample Dilution Factor** (number): Dilution applied to the sample before the assay (1 = undiluted). - **Decimal Places** (number) ## When to use - Quantify unknown protein samples from BCA assay A562 readings. - Fit a standard curve and review its slope, intercept, and R² value. - Correct calculated concentrations for a known sample dilution factor. ## How it works - Enter one protein standard per line as concentration in µg/mL followed by its A562 reading. - Enter one A562 absorbance value for each unknown sample. - The calculator fits the standards with least-squares regression and inverts the curve to estimate each unknown. - It applies the dilution factor and returns concentrations, fit metadata, and flags for readings outside the standard range. ## Use cases - Estimate protein concentration in lysate or purified-protein samples from microplate BCA readings. - Compare unknown samples against a standard curve while accounting for pre-assay dilution. - Check curve quality with regression metadata before interpreting calculated concentrations. ## Frequently asked questions ### What data does the calculator require? It requires protein standards in µg/mL with matching A562 readings, unknown A562 values, and a sample dilution factor. ### Which separators can I use between standard values? Use commas, semicolons, tabs, or spaces between the concentration and A562 value. ### How is the protein concentration calculated? The calculator fits a curve, solves for concentration from each unknown A562 value, and applies the sample dilution factor. ### What does an extrapolation flag mean? It means the unknown absorbance falls outside the absorbance range covered by the standards, so the result is an extrapolation. ### Is this calculator intended for clinical or diagnostic use? No. It is provided for educational use and laboratory planning. ## Related tools - [Bradford Assay Calculator (BSA Standard Curve)](https://elysiatools.com/en/tools/bradford-assay-calculator): Least-squares BSA curve, back-calculated unknowns with dilution factor, extrapolation flags, and protein-specific dye-response caveats. 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