Frequently Asked Questions
Everything you need to know about Fitness Logic.
Getting Started
Do I need to create an account?
No! Fitness Logic works entirely in your browser using local storage by default. Your profile, history, goals, and preferences are stored locally on your device. No sign-up required, and your data never leaves your computer. Creating an account is completely optional and only useful if you want to sync your data across multiple devices.
Why do I need to set up a profile?
Your profile (age, weight, height, sex, and activity level) powers all calculators on the site. Once you enter your stats, every calculator automatically uses them—no need to re-enter your information on each tool. This ensures consistent, accurate calculations across the entire site.
How do I get started?
Start with the Foundations page, which walks you through the essential calculators for beginners: TDEE (calories), BMI, and Ideal Weight. These three tools give you everything you need to begin your fitness journey.
What's the difference between beginner and advanced calculators?
Beginner calculators (like TDEE, BMI, Ideal Weight) provide essential information everyone needs. Advanced calculators (like FFMI, Genetic Potential, Strength Standards) are for experienced fitness enthusiasts who want deeper insights into their training and body composition.
Calculations & Accuracy
How accurate are the calculations?
All formulas used on Fitness Logic are scientifically validated and peer-reviewed. We use established equations like the Mifflin-St Jeor equation for BMR, Epley/Brzycki for 1RM estimation, and the Devine formula for ideal body weight. However, these are estimates—individual results may vary based on genetics, training history, and other factors.
Which 1RM formula should I use?
The Epley formula is generally more accurate for reps 1-10, while Brzycki tends to be more conservative. Both are widely used in strength training. For most people, Epley is recommended. Try both and see which aligns better with your actual 1RM when you test it.
Why does my TDEE seem high/low?
TDEE calculations are estimates based on population averages. Your actual TDEE depends on many factors: muscle mass, metabolism, NEAT (non-exercise activity thermogenesis), and more. Use the step-based method for more accuracy, and adjust based on your results over 2-3 weeks of tracking.
Are the strength standards accurate?
Strength standards are based on population data and represent typical strength levels for different experience categories. They're useful for general comparison, but individual genetics, training history, and body composition significantly impact strength potential. Focus on progress relative to yourself, not just population comparisons.
Data & Privacy
Where is my data stored?
All your data is stored locally in your browser's localStorage. This means your profile, calculation history, goals, and preferences never leave your device. We don't have servers, databases, or any way to access your information.
What happens if I clear my browser data?
If you clear your browser's localStorage, all your saved data (profile, history, goals, favorites, presets) will be deleted. This is a one-way action—we can't recover it. Consider exporting your history before clearing data if you want to keep records.
Can I use Fitness Logic on multiple devices?
By default, data is stored locally on each device. If you use Fitness Logic on your phone and computer, they'll have separate data. However, if you create an account (optional), your data will sync across all your devices—view your calculation history, goals, and presets anywhere.
Why would I want to create an account?
Creating an account (optional) gives you: (1) Cross-device sync – access your profile, history, and presets from any device, (2) Data backup – never lose your calculation history if you clear your browser, (3) Long-term progress tracking – see trends over months and years. Without an account, everything still works perfectly—your data just stays on that one device.
Do you track my usage?
No. We don't use analytics, cookies, or any tracking tools. Your privacy is important to us. Everything runs locally in your browser.
Features & Usage
How do favorites work?
Click the star icon (☆) on any calculator card to add it to your favorites. Your favorites appear at the top of the home page for quick access. This is especially useful if you regularly use the same few calculators.
What are presets?
Presets let you save calculator configurations (like your TDEE settings) and quickly load them later. For example, you could save "Cutting" and "Bulking" presets for the TDEE calculator with different goals and macro splits.
Can I share my calculations?
Yes! Most calculators have a "Share" button that lets you download your results as an image. You can also use the "Share Link" feature (where available) to create a shareable URL with your settings.
How do I export my calculation history?
Go to the History page and click "Export CSV" to download all your saved calculations as a spreadsheet. This is useful for tracking progress over time or backing up your data.
What's the difference between BMR and TDEE?
BMR (Basal Metabolic Rate) is the calories your body burns at complete rest—just to stay alive. TDEE (Total Daily Energy Expenditure) includes BMR plus all your daily activity (exercise, walking, work, etc.). TDEE is what you use to set your calorie targets.
Technical
Does Fitness Logic work on mobile?
Yes! The site is fully responsive and works great on phones and tablets. All calculators are touch-friendly, and the navigation adapts to smaller screens.
Do I need an internet connection?
You need internet to load the site initially, but once loaded, most features work offline. However, some features (like sharing images) may require an active connection.
Which browsers are supported?
Fitness Logic works on all modern browsers: Chrome, Firefox, Safari, Edge, and mobile browsers. We recommend using the latest version of your browser for the best experience.
Why are some calculators missing?
We're constantly adding new calculators. If you have a suggestion, please contact us! We prioritize calculators based on scientific validity, user demand, and practical utility.
Health & Safety
Are these calculators medical advice?
No. Fitness Logic provides educational tools and estimates based on scientific formulas. These are not substitutes for professional medical, nutritional, or fitness advice. Always consult healthcare professionals for personalized guidance.
I'm concerned about my relationship with food. Should I use these calculators?
If you're struggling with disordered eating, please consult a healthcare professional. While our tools are designed for general health guidance, calorie and nutrition calculators can be triggering for some individuals. We've added disclaimers on relevant calculators, but your mental health comes first.
Can I use these calculators while pregnant or breastfeeding?
Pregnancy significantly alters your nutritional needs—please consult a healthcare provider. For breastfeeding, we now support this! Set your breastfeeding status in your profile (partial or exclusive), and our TDEE calculator will automatically add the appropriate calories (+330 kcal/day for partial, +500 kcal/day for exclusive) based on CDC and WHO guidelines.
Are the ideal weight ranges accurate for everyone?
Ideal weight is a range, not a fixed number. The formulas we use are population-based estimates. Individual factors like muscle mass, bone density, and body composition mean your "ideal" weight may differ. Focus on health markers (energy, strength, blood work) rather than hitting a specific number.