🧪 Pharmaceutical QC Calculation Tool

Linearity Calculator — Standard Weight & Dilution Method

Free method-validation linearity calculator for HPLC and UV-Vis. Build as many concentration levels as your protocol needs — label each one yourself (80%, 90%, 100%... or any custom scheme) — then enter replicate response readings in a familiar, Excel-style table. Add a reading column to every level at once with one click, or add a whole new level row. Get instant slope, intercept, correlation coefficient (r), R², %Y-intercept, a regression chart, pass/fail verdict, full step-by-step math log, and a built-in Beginner Tips & Guide — no manual calculation needed.

🔬 HPLC / UV-Vis 📐 Linearity (Weight & Dilution Method) ➕ Unlimited Custom Levels 🧮 Excel-Style Table 📊 Slope, Intercept, r & R² 📈 Regression Chart ✅ Configurable Acceptance Criteria 📘 Beginner Tips & Guide

📐 Linearity Calculator 📘 Beginner Tips & Guide

🧪 Linearity Calculator

Standard Weight & Dilution Method

Formula Used

Conc. (Level) = Weight of Standard (mg) × Dilution Factor
Slope (m) = Σ(x−x̄)(y−ȳ) ÷ Σ(x−x̄)² | Intercept (c) = ȳ − m·x̄
r = Σ(x−x̄)(y−ȳ) ÷ √[Σ(x−x̄)² × Σ(y−ȳ)²] | R² = r²

Instrument Type

Select Instrument

Updates the response label everywhere below — table, results, chart & print report

Standard Preparation

Weight of Standard (mg)

Weight taken to prepare your stock standard solution

Acceptance Limit (min. r)

Minimum correlation coefficient per your method SOP

Decimal Places (display only)

System Suitability — Standard Replicate Injections

Include System Suitability in this calculation (optional — uncheck to skip this section entirely)

Enter each standard replicate injection reading below (typically 5). Mean, SD and %RSD are calculated automatically — matching the System Suitability block on your source calculation sheet.

%RSD Acceptance Limit

Count = 0 | Mean = – | SD = – | %RSD = –

Levels & Replicate Readings (Excel-Style Table)

Type your own % Level for every row — as many levels as your protocol needs. Click ➕ Add Cell to add one reading column to every level at once, just like inserting a column in Excel. Click ➕ Add Level to add a new row.

Levels = 0 | Reading Columns = 0 | Target 100% Concentration = –

🧪 System Suitability — Results

Standard Replicate Injections

#	Peak Area

Correlation Coefficient (r)

Strength of linear fit

R² (Coeff. of Determination)

r squared

Slope (m)

Response per unit conc.

Y-Intercept (c)

Response at zero conc.

📋 Regression Summary

Level-Wise Data & Descriptive Profile

Levels (n)

Mean Conc. (x̄)

Mean Response (ȳ)

%Y-Intercept (of 100%)

Regression Equation

#	Level (%)	Dilution Factor	Peak Area Readings	Average Peak Area	Concentration (mg/mL)

Result	Slope (m)	–
	Y-Intercept (c)	–
	Correlation Coefficient (r)	–
	Coefficient of Determination (R²)	–

📈 Regression Chart

Concentration vs Average Peak Area

Data Points & Fitted Regression Line

🔢 Mathematical Log

Step-by-Step Calculation Trace

Step 0 — System Suitability (Mean / SD / %RSD)

Standard replicate injections — mean, standard deviation and %RSD:

Step 1 — Concentration per Level

Compute each level's concentration as Weight of Standard × its own Dilution Factor:

Step 2 — Average Peak Area per Level

Average the replicate peak area readings entered for each level:

Step 3 — Regression Sums

Compute the mean concentration (x̄), mean response (ȳ), and the sums of squares/cross-products needed for the regression:

Step 4 — Slope & Intercept

Fit the least-squares straight line through the level data:

Step 5 — Correlation Coefficient (r) & R²

Measure how well the data fits the straight line:

⚠️ Disclaimer

BestPharmaTools.com provides this Linearity Calculator strictly for educational and informational purposes. It is an independent, unaffiliated online tool and is not a validated laboratory instrument, controlled GMP document, or a substitute for your organization's approved Quality Management System, Standard Operating Procedures, or review by qualified QA/QC personnel. All data entered is provided solely by the user; BestPharmaTools.com does not verify, endorse, or take responsibility for its accuracy, completeness, or suitability for any regulatory, clinical, or commercial use. Any output — including results viewed, copied, or printed — is used entirely at the user's own discretion and risk. BestPharmaTools.com and its owners/affiliates accept no liability for any decisions, actions, losses, or damages arising from use of this tool. Always verify calculations independently and follow your organization's validated systems and approved SOPs for any official, regulatory, or GMP-related documentation.

Want to understand the science?

Linearity Testing — Beginner Tips & Guide

Learn ICH Q2 acceptance criteria, the reasoning behind slope, intercept, r and R², and how to build a correct level scheme for your method.

Beginner Tips & Guide

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Quality Control Department

Product Name:

Analyzed by / on:

Checked by / on:

Date of Analysis:		Protocol Number:
Analytical Method:		Test:	Linearity

Instrument

Instrument Name:

Instrument Traceability:

Working Standard

Potency:		Reference No:
Weight of Standard:

System Suitability — Raw Data

S.No	Peak Area

Linearity — Raw Data

Results Summary

Result	Slope	–
	Y-intercept	–
	Corelation Cofficent (r)	–
	Cofficient of Determination (R²)	–
Regression Equation		–
Verdict		–

Graphical Presentation — Concentration vs Response