BCA Assay Calculator (Protein Standard Curve)

BCA Assay Calculator (Protein Standard Curve) | Online Free Tool | Elysia Tools

Tool usage guide

Learn when to use this tool, what it supports, and how real users apply it.

Key facts

Category: Education
Input types: textarea, number
Output type: json
Sample coverage: 4
API ready: Yes

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.

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

1Enter one protein standard per line as concentration in µg/mL followed by its A562 reading.
2Enter one A562 absorbance value for each unknown sample.
3The calculator fits the standards with least-squares regression and inverts the curve to estimate each unknown.
4It 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.

Examples

1. Standard-range BCA quantification

Research student

Background

A student measures a BSA standard series from 0 to 2000 µg/mL and records two unknown lysate absorbances.

Problem

They need to convert A562 readings into protein concentrations and confirm that the unknowns fall within the standard curve.

How to use

Enter the standards, add unknown absorbances of 0.735 and 1.640, set the dilution factor to 1, and choose two decimal places.

Standards: 0, 0.000; 200, 0.200; 500, 0.500; 1000, 1.000; 2000, 2.000. Unknowns: 0.735 and 1.640. Dilution factor: 1.

Outcome

The fitted curve is A562 = 0.001c with R² = 1.00. The unknowns are calculated as 735 µg/mL and 1640 µg/mL, both within the curve range.

2. Blank-corrected curve with sample dilution

Laboratory technician

Background

A technician uses standards with a nonzero blank and measures a sample that was diluted fivefold before the BCA assay.

Problem

The in-assay concentration must be corrected to estimate the concentration in the original stock.

How to use

FAQ

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.

Standards: 0, 0.030; 200, 0.230; 500, 0.530; 1000, 1.030. Unknown: 0.530. Dilution factor: 5.

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Learn when to use this tool, what it supports, and how real users apply it.

Key facts

Overview

When to use

How it works

Use cases

Examples

1. Standard-range BCA quantification

2. Blank-corrected curve with sample dilution

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