How every calculator works
Each tool on AI Fit Hub is backed by a methodology page. Formulas, coefficients, data sources, assumptions, approximation range, and known limitations — so you can see exactly what the number means before you use it.
Nutrition
- BMR Calculator Estimate basal metabolic rate and maintenance calories using Mifflin-St Jeor assumptions.
- Creatine Intake Calculator Estimate creatine maintenance and loading doses from body weight and training frequency.
- Food-to-Exercise Converter See how long you need to exercise to burn off any food, personalized by bodyweight.
- Intermittent Fasting Window Planner Plan protocol-based eating and fasting windows with a 24-hour timeline and 5:2 day picker.
- Macro Calculator Convert calorie targets into protein, carbs, and fat grams for your goal.
- Macro Cycling Calculator Calculate different macros for training days and rest days with carb cycling for recomp, lean bulk, or cut goals.
- Meal Macro Split Planner Convert daily macro targets into per-meal protein, carb, and fat execution numbers.
- Protein Intake Calculator Get daily protein targets based on training level and goal.
- TDEE Calculator Estimate your daily energy expenditure with Mifflin-St Jeor + activity factors.
- Water Intake Calculator Calculate daily water intake based on weight, activity level, and climate.
Strength
- DOTS & Wilks Score Calculator Compare powerlifting strength across weight classes with IPF DOTS and Wilks-2020 coefficients.
- DOTS vs Wilks vs GL Calculator Compare DOTS, Wilks, and Goodlift scores side by side to see which system rates your powerlifting total highest.
- Meet Day Attempt Selector Plan powerlifting meet attempts with opener, second, and third attempt suggestions based on 1RM and confidence.
- One-Rep Max Calculator Estimate one-rep max with Epley, Brzycki, and Lombardi formulas.
- Plate Loading Calculator Calculate which weight plates to load on each side of a barbell to hit your target weight in kg or lbs.
- Progressive Overload Planner Project lifting progression with weekly overload and planned deload cycles.
- RPE to Percentage Converter Convert RPE and reps to percentage of 1RM with a full interactive RPE chart based on the Tuchscherer table.
- Strength Percentile Calculator Find out where your squat, bench, deadlift, or OHP ranks against other lifters by bodyweight and sex.
- Strength Standards Calculator Rank your lifts from Beginner to Elite based on bodyweight ratios.
- Workout Volume Calculator Calculate total training volume and compare against optimal ranges per muscle group.
Cardio
- Calories Burned Calculator Estimate exercise calorie burn from body weight, duration, MET intensity, and incline.
- Cycling Power & FTP Zone Calculator Calculate your 7 Coggan power training zones from FTP or a 20-minute test result with W/kg ratio.
- Race Time Predictor Predict finish times across 5K, 10K, half marathon, and marathon from any known race result using Riegel's formula.
- Resting Heart Rate Calculator Assess cardiovascular fitness from your resting heart rate — classification, cardio age, and improvement targets.
- Run Training Paces Calculator Get personalized Easy, Tempo, Threshold, Interval, and Speed training paces from a recent race time using the Daniels VDOT method.
- Running Pace Calculator Calculate pace per km and mile and project race finish times from one run.
- Swim Pace Calculator Calculate swim pace, total time, or distance with SWOLF and effort-zone context.
- Treadmill Pace Converter Convert treadmill speed to running pace with incline-adjusted flat equivalent, projected race times, and calorie estimates.
- VO2 Max Estimator Estimate aerobic capacity with Cooper run, Rockport walk, or no-exercise questionnaire methods.
- Walking Calorie Calculator Estimate calories burned from walking using speed, duration, body weight, and incline.
- Zone 2 Heart Rate Calculator Calculate your Zone 2 heart rate with Maffetone, Karvonen, % Max HR, and lactate threshold methods compared side by side.
Body Composition
- BMI Calculator Calculate BMI quickly with a plain-language range explanation and limitations.
- Body Fat Percentage Calculator Estimate body fat percentage using the U.S. Navy circumference method.
- FFMI Calculator Calculate Fat-Free Mass Index to gauge muscularity and compare against natural benchmarks.
- Flexibility Score Calculator Estimate your flexibility percentile and rating from a sit-and-reach test score, adjusted for age and sex.
- Ideal Weight Calculator Compare Devine, Robinson, Miller, and Hamwi formulas as a realistic range.
- Lean Body Mass Calculator Estimate lean body mass using Boer, James, Hume, and Peters formulas from height and weight.
- Muscle Gain Potential Calculator Estimate your natural muscular potential with the Casey Butt model and see how close you are to your genetic limit.
- Waist-to-Hip Ratio Calculator Calculate waist-to-hip ratio and assess body composition using WHO guidelines.
Recovery
- Heart Rate Zone Calculator Calculate personalized training zones with the Karvonen method.
- Sleep Calculator Calculate optimal bed and wake times based on 90-minute sleep cycles.
- Sleep Debt Calculator Track 7 nights of sleep to calculate accumulated sleep debt with a recovery timeline and quality assessment.
- Sweat Rate Calculator Calculate your personal sweat rate from pre/post-exercise weigh-ins and estimate fluid and sodium losses using ACSM guidelines.
Planning
- Body Recomposition Planner Plan body-fat reduction pace, deficit targets, and protein needs around a timeline.
- Calorie Deficit Calculator Estimate required daily calorie deficit for a target timeline and bodyweight change.
- Hybrid Training Planner Build a weekly schedule that balances running and lifting with interference warnings and recovery guidance.