Our Methodology

Every formula used in our calculators is sourced from one or more of the following:

• Peer-reviewed scientific journals — including publications from PubMed, Frontiers in Physiology, the Journal of Strength and Conditioning Research, the British Journal of Sports Medicine, and similar academic sources.
• Established fitness science organizations — such as the National Academy of Sports Medicine (NASM), the American College of Sports Medicine (ACSM), the National Strength and Conditioning Association (NSCA), and the American Council on Exercise (ACE).
• Widely accepted industry standards — formulas and protocols that have been validated across multiple studies and are commonly used in professional fitness settings, university exercise science programs, and certified training curricula.

We cite our sources directly on each calculator page, typically in the educational content section and within FAQ answers. Where a direct link to the original publication is available, we provide it. We do not use proprietary, unverified, or anecdotal formulas.

When multiple formulas exist for the same calculation, we follow a structured evaluation process to determine which formulas to implement:

1. Validation breadth — We prioritize formulas that have been independently validated across multiple studies, populations, and demographics rather than those tested in a single study.
2. Industry adoption — Formulas widely adopted by certification bodies (NASM, ACSM, NSCA) and used in professional practice receive higher consideration.
3. Recency and relevance — Where newer research provides meaningfully improved accuracy over older formulas, we incorporate the updated versions while noting the original.
4. User choice — Where multiple validated formulas exist with different strengths (for example, Epley vs. Brzycki for one-rep max estimation), we implement all major options and let you choose which one to use. We clearly identify which formula is being applied and explain the differences.

We do not invent our own formulas, modify published formulas without disclosure, or present estimation methods as more accurate than they are.

It is important to understand what our calculators can and cannot do:

• Our calculators provide estimates based on population averages and published scientific formulas. They are not precision instruments and should not be treated as definitive measurements.
• Individual results may vary significantly based on factors including but not limited to genetics, training history, body composition, age, sex, nutrition, sleep quality, stress levels, and individual biomechanics.
• Formulas derived from population studies have inherent limitations. Most were validated on specific demographic groups and may be less accurate for individuals outside those groups.
• We clearly state limitations on each calculator page. We do not present estimates as facts, and we always recommend that users consider their unique circumstances when interpreting results.

Our tools are designed to provide useful reference points and general awareness of fitness metrics. They are informational tools, not diagnostic instruments, and are not intended to replace the guidance of qualified professionals.

Every calculator goes through a multi-step quality assurance process before publication:

1. Research verification — All cited research papers and sources are read, verified, and cross-referenced before formulas are implemented.
2. Formula implementation review — The mathematical implementation of every formula is reviewed against the original publication to ensure accurate translation from research paper to code.
3. Edge case testing — Calculators are tested with boundary values, unusual inputs, and edge cases to ensure they handle all realistic scenarios without producing errors, NaN values, or misleading results.
4. Cross-validation — Where possible, results are compared against other established calculators and known reference values to confirm consistency.
5. Content review — All educational content, FAQ answers, and descriptive text are reviewed for accuracy, clarity, and compliance with our informational-only positioning.

Our approach to user data is straightforward and uncompromising:

• All calculations are performed entirely in your browser. Your measurements, inputs, and results are never sent to our servers or any third-party service.
• When progress tracking features are available, data is stored locally on your device using your browser's built-in storage (localStorage). This data is accessible only to you and can be cleared at any time through your browser settings.
• We do not collect personal information through our calculators. We do not use analytics tools that track individual calculator inputs or results.
• We do not sell, share, or transmit user data to any third party for any purpose.

For complete details, please review our Privacy Policy.

Fitness science is not static. New research is published regularly, and our commitment is to keep our tools current and accurate:

• We regularly review published research to identify new findings that may affect the accuracy or relevance of our existing calculators.
• When significant new research emerges that improves upon the formulas we use, we update our calculators accordingly and note the changes.
• Each calculator page displays its last update date so you can verify the information is current.
• We actively monitor user feedback and bug reports to identify and resolve issues promptly.
• Outdated or superseded formulas are noted as such but may be retained as alternative options where they remain widely used in the fitness community.

All content on FitLifeRegime adheres to strict content standards:

• Our tools are positioned strictly as informational calculators and personal awareness utilities. They do not provide personalized recommendations, diagnoses, or professional-level guidance.
• We use neutral, non-clinical language throughout. We do not make claims about preventing, treating, or diagnosing any condition.
• All calculator descriptions and educational content are reviewed to ensure they remain within the scope of general fitness information and do not cross into professional guidance territory.
• We include appropriate disclaimers on every calculator page and throughout the website to ensure users understand the informational nature of our tools.

If you have questions about our methodology, notice an error in any of our calculators, or want to suggest improvements, we welcome your feedback. Please contact us and include as much detail as possible so we can investigate thoroughly.

We take accuracy seriously. If you believe a formula has been implemented incorrectly or a cited source is inaccurate, we will review the concern promptly and make corrections where warranted.