Online F1 and F2 Calculator

In pharmaceutical development, comparative dissolution studies are critical for assessing the similarity between two drug products — typically a generic formulation and an innovator (reference) product. Regulatory bodies such as the US FDA, EMA, and WHO require statistical tools to evaluate these similarities rigorously. The difference factor (F1) and the similarity factor (F2) are among the most widely accepted methods.

To simplify this analysis, the F1 and F2 Calculator has become an essential digital tool for pharmaceutical researchers and formulators. This blog post offers an in-depth overview of how these factors work, how the calculator functions, and its importance in bioequivalence studies and regulatory submissions.

What are F1 and F2 Factors? 

1. F1 (Difference Factor): Measures the percent difference between two dissolution curves at each time point. It focuses on the absolute difference in release profiles. Acceptable Range: 0 to 15 
2. F2 (Similarity Factor): A logarithmic reciprocal square root transformation of the sum of squared errors between test and reference products. Acceptable Range: 50 to 100 

Features of the F1 and F2 Calculator 

The F1 and F2 calculator streamlines the comparison process by providing: 

✅ Input fields for multiple time points of dissolution data 

✅ Instant calculation of F1 and F2 values 

✅ Visual comparison via overlayed dissolution profiles 

✅ Compliance checking with regulatory guidelines 

✅ Exportable reports (PDF/Excel) for regulatory filing 

Importance in the Pharmaceutical Industry 

The use of F1 and F2 factors is critical in demonstrating bioequivalence, especially in: 

💊 Generic drug approvals 

🧪 Formulation changes 

📄 Post-approval variations 

📦 Batch-to-batch consistency 

The test and reference products are deemed similar when the F2 value falls within 50–100, reducing the need for expensive in vivo bioequivalence studies. Thus, the calculator saves both time and cost in the drug development lifecycle.

 

How to Use the Calculator?

1. Collect dissolution data at identical time points for both test and reference batches. 
2. Enter the values in the calculator’s data grid. 
3. Click ‘Calculate’ to get instant F1 and F2 values. 
4. Interpret results: 

• If F2 > 50 and F1 < 15 → Dissolution profiles are similar 
• Otherwise, → Reformulation or additional testing may be needed 

Limitations and Guidelines

• Do not use more than one time point after 85% dissolution 
• Exclude initial time points (<15 min) if more than 85% drug is dissolved
• Use at least 3 time points (excluding zero)

Who Should Use It? 

• Formulation scientists 
• Regulatory affairs professionals 
• R&D and QA teams 
• Pharmacokinetics researchers 
• CROs involved in generic drug development

The F1 and F2 Calculator is a powerful, regulation-compliant tool to ensure your formulations meet bioequivalence standards with statistical confidence. Whether you're submitting a generic ANDA or validating formulation changes, this calculator provides a scientifically robust and user-friendly solution. By integrating this calculator into your dissolution testing workflow, you can significantly accelerate your regulatory approval timelines while maintaining the highest standards of quality and compliance.

F1 & F2 Dissolution Calculator

Important Notes:

• Enter dissolution mean value of 12 units each (reference product/pre-changed product and test product/post-change product).
• The dissolution measurements of the test and reference batches should be made under exactly the same conditions.
• The dissolution time points for both the profiles should be the same (e.g., 15, 30, 45, 60 minutes).
• Only one measurement should be considered after 85% dissolution of both the products.
• To allow use of mean data, the percent coefficient of variation (RSD) at the earlier time points (e.g., 15 minutes) should not be more than 20%, and at other time points should not be more than 10%.
• For curves to be considered similar, f1 values should be close to 0, and f2 values should be close to 100. Generally, f1 values up to 15 (0-15) and f2 values greater than 50 (50-100) ensure sameness or equivalence of the two curves and, thus, of the performance of the test and reference products.
• Most countries recommend that where more than 85% of the drug is dissolved for both the test and reference products within 15 min, dissolution profiles may be accepted as similar without further mathematical evaluation.

Reference Product

Test Product

Product Name:

Batch/Lot Number:

Mfg. Date:

Expiry Date:

Dissolution Data

Sr.No.	Dissolution Time (min)	Mean Drug Release (%) - Reference	Mean Drug Release (%) - Test	Action

No. of Time Points:

Similarity Factor (f2):

Difference Factor (f1):

Terms of Use for Pharma Tools - F1 & F2 Dissolution Calculator

By using this tool, you agree to the following terms and conditions:

Usage Rights: This tool is provided for informational and educational purposes only. It is intended to assist with the calculation of dissolution profile comparisons in a basic regulatory context and is not a substitute for professional judgment or regulatory advice.

Accuracy: While every effort has been made to ensure the accuracy of the tool's calculations and outputs, we do not guarantee that the results are free from errors. Users are advised to independently verify any results obtained through this tool.

Limitation of Liability: We are not liable for any damages, losses, or consequences that may arise from the use or misuse of the tool. The tool is provided "as is" without any warranties of any kind, either express or implied, including but not limited to warranties of merchantability, fitness for a particular purpose, and non-infringement.

Intellectual Property: All content, design, and functionality of this tool are for demonstration purposes. If based on existing IP, it should be respected.

Privacy: The tool does not collect personally identifiable information. Any data entered is processed locally in your browser.

Modifications: We reserve the right to modify, suspend, or discontinue the tool at any time without prior notice.

Compliance: Users must ensure compliance with all applicable regulations and guidelines while using this tool.

By using this tool, you acknowledge that you have read, understood, and agreed to these terms and conditions.