# HealthCalc.app — Full Documentation for LLMs & AI Assistants

> Free, evidence-based health and fitness calculators built with peer-reviewed clinical formulas. Designed to be fast, client-side, private, and accessible with zero sign-up or paywalls.

Website: https://healthcalc.app

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## 1. Energy & Calorie Calculators

### TDEE Calculator
- **URL**: https://healthcalc.app/tdee-calculator/
- **Description**: Calculates Total Daily Energy Expenditure (maintenance calories) and basal metabolic rate.
- **Formulas**: Mifflin-St Jeor, Harris-Benedict (revised 1984), Katch-McArdle (LBM-based), Schofield.
- **Inputs**: Biological sex, age (years), height (cm/in), weight (kg/lbs), activity level (sedentary 1.2 to extra active 1.9), optional body fat percentage, optional daily step count.
- **Outputs**: Baseline TDEE (kcal/day), BMR (kcal/day), weight loss deficit calories (-500 kcal for 1 lb/wk, -1000 kcal for 2 lbs/wk), weight gain surplus calories (+250 to +500 kcal), macronutrient targets for balanced, low-carb, and high-protein splits.

### BMR Calculator
- **URL**: https://healthcalc.app/bmr-calculator/
- **Description**: Calculates Basal Metabolic Rate — the minimum calories required to sustain vital organ functions at rest.
- **Formulas**: Mifflin-St Jeor (clinical standard), Revised Harris-Benedict, Schofield (WHO), Katch-McArdle.
- **Inputs**: Biological sex, age, height, weight, optional body fat %.
- **Outputs**: BMR in kcal/day for all 4 equations, formula comparison chart, minimum calorie safety floor guidelines, and hourly metabolic breakdown.

### RMR Calculator
- **URL**: https://healthcalc.app/rmr-calculator/
- **Description**: Computes Resting Metabolic Rate and compares differences between BMR and RMR including TEF and minimal movement.
- **Formulas**: Cunningham equation (1980/1991), Mifflin-St Jeor, Owen formula, Harris-Benedict.
- **Inputs**: Sex, age, weight, height, optional lean body mass / body fat %.
- **Outputs**: RMR in kcal/day, comparison to BMR, metabolic adaptation adjustment, energy expenditure by organ system.

### Calorie Deficit Calculator
- **URL**: https://healthcalc.app/calorie-deficit-calculator/
- **Description**: Estimates customized calorie deficit targets for sustainable fat loss with adaptive metabolic timelines.
- **Formulas**: 3,500 kcal/lb fat mass rule with Hall (NIH) adaptive metabolic downregulation adjustments.
- **Inputs**: Age, sex, height, weight, activity level (or direct maintenance calories), target goal weight, fat loss pace (0.5 lb, 1 lb, 1.5 lb, 2 lb per week).
- **Outputs**: Daily cutting calorie target, daily deficit size, estimated date of goal completion, week-by-week weight loss projection curve, macro splits, and catabolism risk warnings.

### Macro Calculator
- **URL**: https://healthcalc.app/macro-calculator/
- **Description**: Computes optimal daily protein, carbohydrate, and fat targets in grams and calories.
- **Formulas**: 4 kcal/g for protein and carbs, 9 kcal/g for fats. Dynamic protein allocation based on lean mass and training goal.
- **Inputs**: Goal (Fat Loss, Maintenance, Muscle Gain), calorie target (calculated from biometrics or custom entered), diet preset (Balanced 40/30/30, High Protein 40/35/25, Low Carb 25/50/25, Keto 5/25/70, Custom).
- **Outputs**: Protein (g), Carbohydrates (g), Fats (g), total calories, per-meal breakdown (2, 3, 4, 5, or 6 meals/day), stacked visual nutrient bar.

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## 2. Body Composition Calculators

### Body Fat Calculator
- **URL**: https://healthcalc.app/body-fat-calculator/
- **Description**: Multi-method body fat estimation tool.
- **Formulas**: US Navy Circumference Method (Hodgdon & Beckett), Jackson-Pollock 3-Site Caliper (Chest/Abdomen/Thigh for men; Triceps/Suprailiac/Thigh for women via Siri equation), YMCA formula, BMI conversion method (Deurenberg).
- **Inputs**: Biological sex, height, weight, neck circumference, waist circumference, hip circumference (females), skinfold caliper readings (optional).
- **Outputs**: Body fat percentage across all methods, Lean Body Mass (lbs/kg), Fat Mass (lbs/kg), ACE fitness category (Essential Fat, Athletes, Fitness, Average, Obese), ideal body fat range.

### BMI Calculator
- **URL**: https://healthcalc.app/bmi-calculator/
- **Description**: Computes standard Quetelet BMI and Oxford New BMI (Nick Trefethen) with pediatric CDC percentiles.
- **Formulas**: Standard BMI = weight(kg) / height(m)²; New BMI = 1.3 × weight(kg) / height(m)^2.5; CDC LMS parameters for children 2-20.
- **Inputs**: Age, biological sex, height, weight, optional waist circumference.
- **Outputs**: Standard BMI, New BMI, WHO weight category (Underweight, Normal, Overweight, Obese Class I/II/III), CDC percentile (for youth), healthy weight range deltas (lbs/kg to normal range), WHtR cross-check.

### FFMI Calculator
- **URL**: https://healthcalc.app/ffmi-calculator/
- **Description**: Calculates Fat-Free Mass Index to evaluate muscularity independent of height and determine natural genetic limits.
- **Formulas**: Raw FFMI = Lean Mass (kg) / Height (m)²; Height-Adjusted FFMI = Raw FFMI + 6.1 × (1.8 - Height(m)) based on Kouri et al. (1995).
- **Inputs**: Biological sex, height, weight, body fat %.
- **Outputs**: Raw FFMI, Height-Adjusted FFMI, lean mass, fat mass, muscularity tier (Below Average to Near Natural Limit / Enhanced >25), maximum natural lean mass ceiling.

### Lean Body Mass Calculator
- **URL**: https://healthcalc.app/lean-body-mass-calculator/
- **Description**: Estimates fat-free body weight using biometric equations.
- **Formulas**: Boer formula (1984), James formula (1976), Hume formula (1966), and Katch-McArdle (with known body fat).
- **Inputs**: Sex, age, height, weight, optional body fat %.
- **Outputs**: LBM in kg and lbs for all formulas, comparative table, body fat mass, percentage breakdown.

### Ideal Weight Calculator
- **URL**: https://healthcalc.app/ideal-weight-calculator/
- **Description**: Calculates target healthy body weight across clinical and aesthetic equations.
- **Formulas**: Robinson (1983), Devine (1974), Hamwi (1964), Miller (1983), and WHO BMI healthy range (18.5 - 24.9).
- **Inputs**: Biological sex, height, body frame size (small, medium, large via wrist circumference).
- **Outputs**: Target weight range in lbs/kg for each equation, frame-adjusted target, WHO healthy weight interval.

### Waist-to-Hip Ratio Calculator (WHR)
- **URL**: https://healthcalc.app/waist-to-hip-ratio-calculator/
- **Description**: Evaluates abdominal visceral adiposity, cardiometabolic disease risk, and aesthetic body shape.
- **Formulas**: WHR = Waist / Hip. WHO risk thresholds (Men: low <0.90, moderate 0.90-0.95, high >0.95; Women: low <0.80, moderate 0.80-0.85, high >0.85). Golden ratio = 0.70 (women), 0.85-0.90 (men).
- **Inputs**: Waist circumference, hip circumference, biological sex, optional age/height/weight.
- **Outputs**: WHR score, WHO cardiovascular risk classification, body shape category (Hourglass, Pear, Apple, Rectangle), Golden Ratio comparison, interactive body shape SVG.

### Waist-to-Height Ratio Calculator (WHtR)
- **URL**: https://healthcalc.app/waist-to-height-ratio-calculator/
- **Description**: Early cardiometabolic risk screening tool and military body composition standard.
- **Formulas**: WHtR = Waist / Height. Ashwell boundary ("Keep your waist to less than half your height" — WHtR < 0.50). US DoD military body fat tape equations.
- **Inputs**: Waist circumference, height, biological sex, age.
- **Outputs**: WHtR ratio, Ashwell health category (Take Care, Healthy, Consider Action, Take Action), DoD military compliance status, visceral fat risk rating.

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## 3. Nutrition & Macro Calculators

### PSMF Calculator (Protein Sparing Modified Fast)
- **URL**: https://healthcalc.app/psmf-calculator/
- **Description**: Calculates daily macros, Lyle McDonald Category 1, 2, and 3 classifications, safe diet duration, structured refeed schedules, food equivalents, and mandatory electrolyte protocols for rapid adipose fat loss on a Protein Sparing Modified Fast.
- **Formulas**: Mifflin-St Jeor / Katch-McArdle LBM baseline BMR. Lyle McDonald Category thresholds (Cat 1: Men <=15%, Women <=24% BF, 11-12 days max, 0 free meals, 2-3 day refeed; Cat 2: Men 16-25%, Women 25-34% BF, 2-6 weeks, 1 free meal/wk, 5-hr refeed; Cat 3: Men >=26%, Women >=35% BF, 6-12 weeks, 2 free meals/wk). Protein multipliers: 0.8-2.0 g/lb LBM based on category and training type. Strict ~20g trace carb and trace fat caps.
- **Inputs**: Biological sex, age, weight, height, activity type (Inactive, Aerobic, Resistance Training), optional body fat %, optional custom carb/fat caps.
- **Outputs**: Daily PSMF calories, maintenance TDEE, daily & weekly caloric deficit, estimated weekly fat loss, protein anchor grams & kcal, trace carbs & fat grams & kcal, macro circular SVG rings, category protocol timeline (max duration, free meals, refeed type, diet break length), single whole food equivalents (chicken breast, 99% lean turkey, cod/white fish, egg whites, tuna in water), and clinical electrolyte shield (Sodium 4000mg, Potassium 1000mg, Magnesium 400mg, Calcium 1000mg, Omega-3 Fish Oil 4-5g, fluid intake).

### Body Recomposition Calculator
- **URL**: https://healthcalc.app/body-recomposition-calculator/
- **Description**: Calculates exact daily calories, macronutrient targets, and training vs. rest day calorie cycling to build muscle and burn body fat simultaneously. Includes a 12-week body transformation projection simulator and leucine-optimized meal splits.
- **Formulas**: Mifflin-St Jeor / Katch-McArdle LBM baseline BMR, Barakat et al. (2020) and Morton et al. (2018) protein targets (1.0–1.2 g/lb LBM / 2.2–2.6 g/kg LBM), Calorie cycling (+5% surplus on workout days for MPS, -15% deficit on rest days for fat oxidation).
- **Inputs**: Biological sex, age, weight, height, activity level, training experience level (Beginner, Returning Lifter, Skinny-Fat, Intermediate/Advanced), recomp strategy (Calorie Cycling vs. Constant Deficit), weekly lifting days (3–6), optional body fat %, and customizable protein ratio.
- **Outputs**: Average daily calories, maintenance TDEE, net weekly deficit, training day vs rest day calorie and macro breakdown (Protein, Carbs, Healthy Fats with interactive SVG circular rings), 12-week transformation projection timeline (weeks 0, 4, 8, 12 fat mass vs lean mass), biological recomp potential diagnostic, baseline biometrics (LBM and fat mass), and per-meal protein distribution with leucine threshold validation.

### Keto Macro Calculator
- **URL**: https://healthcalc.app/keto-calculator/
- **Description**: Calculates personalized ketogenic macronutrient distributions, net carbs limits, lean mass protein targets, and electrolyte protocols.
- **Formulas**: Mifflin-St Jeor / Katch-McArdle LBM energy equation, 4 kcal/g protein & carbs, 9 kcal/g fat. Rule structure: Carbs = Hard Limit, Protein = Target Goal based on LBM (0.8-1.2 g/lb), Fat = Caloric Satiety Lever.
- **Inputs**: Biological sex, age, weight, height, activity level, goal (Fat Loss, Maintenance, Muscle Gain), deficit/surplus %, optional body fat %, net carb limit (default 20g), protein ratio, keto preset (Standard SKD, High-Protein / Ketogains, Therapeutic).
- **Outputs**: Daily Calories, Net Carbs (g & kcal), Protein (g & kcal), Fat (g & kcal), macro percentage distribution, per-meal breakdown (2 meals, 3 meals, 4 meals, OMAD), daily electrolyte shield (Sodium, Potassium, Magnesium, Hydration in L/oz), time to ketosis estimate, target blood ketone range (0.5–3.0 mmol/L).

### Carnivore Diet Calculator
- **URL**: https://healthcalc.app/carnivore-diet-calculator/
- **Description**: Determines macronutrients, caloric needs, and daily meat/animal food portions for zero-carb and carnivore diets.
- **Formulas**: Ketogenic energy partitioning (80:20 fat:protein for therapeutic ketosis, 70:30 standard, 60:40 high protein/cutting). USDA nutrient database food density.
- **Inputs**: Sex, age, weight, height, activity level, carnivore goal (Fat Loss, Performance, Hypertrophy), fat ratio preset.
- **Outputs**: Daily calories, Protein (g), Fat (g), Carbs (0g), exact food portion equivalents (oz/grams of 80/20 ground beef, ribeye steak, eggs, butter, beef tallow).

### Cutting Calculator
- **URL**: https://healthcalc.app/cutting-calculator/
- **Description**: Bodybuilding fat loss planner with muscle preservation and carb refeed cycling.
- **Formulas**: Katch-McArdle / Mifflin BMR, Alpert's maximum fat oxidation rate equation (69 kcal/kg fat mass/day) to prevent muscle catabolism.
- **Inputs**: Sex, age, weight, height, body fat %, goal target body fat %, deficit pace (0.25% to 1.0% body weight/week), optional carb cycling toggle.
- **Outputs**: Cutting calories, protein target (2.0-2.4 g/kg LBM), carb & fat distribution, catabolism safety warning, 5 low-carb / 2 high-carb refeed schedule, week-by-week fat loss timeline.

### Reverse Diet Calculator
- **URL**: https://healthcalc.app/reverse-diet-calculator/
- **Description**: Post-diet metabolic restoration roadmap to increase calories without unwanted fat accumulation.
- **Formulas**: Adaptive thermogenesis recovery curve, incremental weekly caloric steps (+2 to +5% per week).
- **Inputs**: Current ending cutting calories, maintenance estimated TDEE, pacing (Conservative, Moderate, Aggressive).
- **Outputs**: Week-by-week calorie and macro targets, estimated duration to full maintenance recovery, fat gain risk probability, water retention expectation guide.

### Carb Cycling Calculator
- **URL**: https://healthcalc.app/carb-cycling-calculator/
- **Description**: Formulates daily carbohydrate and calorie variations matched to workout intensity.
- **Formulas**: High Carb (120-130% TDEE), Moderate Carb (100% TDEE), Low Carb (70-80% TDEE), Zero Carb / Rest Day.
- **Inputs**: Body weight, maintenance calories (TDEE), weekly training schedule (heavy lifting days, light days, rest days).
- **Outputs**: Grams of protein, carbs, and fats for High, Medium, Low, and Rest days; weekly average calorie balance.

### Intermittent Fasting Calculator
- **URL**: https://healthcalc.app/intermittent-fasting-calculator/
- **Description**: Fasting window and meal timing scheduler with circadian and sleep overlap optimization.
- **Formulas**: 16:8 Leangains, 18:6, 20:4 Warrior, 23:1 OMAD, 14:10, 12:12 circadian rhythm schedules.
- **Inputs**: Protocol choice, last meal time / preferred eating start time, bedtime, waking time.
- **Outputs**: Daily eating window hours, fasting window hours, passive sleep fasting hours, active awake fasting hours, interactive 24-hour visual schedule clock.

### Ramadan Fasting Calculator
- **URL**: https://healthcalc.app/ramadan-fasting-calculator/
- **Description**: Nutrition, hydration, and meal distribution calculator tailored for holy Islamic fasting hours.
- **Formulas**: Time-restricted caloric partitioning between Suhoor (pre-dawn meal 35-40%) and Iftar (post-sunset meal 50-55% + optional snack 10%).
- **Inputs**: Daily fasting duration (hours), biometrics, workout timing (before Iftar, after Iftar, before Suhoor), hydration target.
- **Outputs**: Total adjusted TDEE, Suhoor calories and macros (complex carbs + slow-digesting protein), Iftar calories and macros (fast carbs + lean protein), fluid intake schedule during non-fasting window.

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## 4. Fitness & Performance Calculators

### One Rep Max Calculator (1RM)
- **URL**: https://healthcalc.app/one-rep-max-calculator/
- **Description**: Estimates maximum single-rep lifting capacity for barbell and strength training.
- **Formulas**: Brzycki, Epley, Lander, Lombardi, Mayhew, O'Conner, Wathan.
- **Inputs**: Lifted weight (lbs/kg), repetitions completed (1-12), optional Rate of Perceived Exertion (RPE 6.5-10) or Reps in Reserve (RIR).
- **Outputs**: Consensus estimated 1RM, individual formula outputs, complete training percentage table (50% to 95% of 1RM with estimated rep limits), barbell plate loading visualizer (45, 35, 25, 10, 5, 2.5 lb plates or metric equivalents).

### VO2 Max Calculator
- **URL**: https://healthcalc.app/vo2-max-calculator/
- **Description**: Estimates maximal aerobic capacity (ml/kg/min) without clinical gas analysis equipment.
- **Formulas**: Cooper 12-minute run test, Rockport 1-mile walk test, George 1.5-mile submaximal jog test, Non-exercise Jackson physical activity model (Uth–Sørensen–Overgaard–Pedersen).
- **Inputs**: Test type selected, time taken / distance covered, heart rate (for Rockport/George), age, sex, resting heart rate, BMI.
- **Outputs**: VO2 Max in ml/kg/min, ACSM aerobic fitness percentile and classification (Poor to Superior), estimated Cardio Fitness Age, 5 aerobic heart rate training zones.

### Grip Strength Calculator
- **URL**: https://healthcalc.app/grip-strength-calculator/
- **Description**: Dynamometer score analyzer for longevity screening and sarcopenia diagnostics.
- **Formulas**: Mathiowetz et al. (1985) normative data by 5-year age cohorts; EWGSOP2 sarcopenia consensus criteria (<27 kg for men, <16 kg for women).
- **Inputs**: Hand dynamometer reading (kg/lbs), sex, age, hand tested (dominant/non-dominant).
- **Outputs**: Population percentile ranking, EWGSOP2 sarcopenia status, longevity risk rating, sex/age cohort mean comparison.

### Zone 2 Heart Rate Calculator
- **URL**: https://healthcalc.app/zone-2-heart-rate-calculator/
- **Description**: Computes aerobic base and mitochondrial fat-oxidation training heart rate boundaries.
- **Formulas**: Tanaka formula (208 - 0.7 × Age), Gellish (207 - 0.7 × Age), Karvonen Heart Rate Reserve: Target HR = ((HRmax - HRrest) × %intensity) + HRrest.
- **Inputs**: Age, optional resting heart rate (for Karvonen), calculation method.
- **Outputs**: Zone 2 target range (60-70% HRmax or 60-70% HRR in BPM), complete 5-zone table (Zone 1 Active Recovery, Zone 2 Aerobic Base, Zone 3 Tempo, Zone 4 Lactate Threshold, Zone 5 Anaerobic Max).

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## 5. Health & Medical Calculators

### Blood Pressure Calculator
- **URL**: https://healthcalc.app/blood-pressure-calculator/
- **Description**: Blood pressure reading analyzer and cardiovascular risk calculator.
- **Formulas**: AHA/ACC 2017 Blood Pressure Clinical Practice Guidelines. Mean Arterial Pressure: MAP = DBP + 1/3(SBP - DBP). Pulse Pressure: PP = SBP - DBP.
- **Inputs**: Systolic BP (mmHg), Diastolic BP (mmHg), optional age, optional multi-day reading log.
- **Outputs**: AHA Category (Normal, Elevated, Stage 1 Hypertension, Stage 2 Hypertension, Hypertensive Crisis), MAP (mmHg), Pulse Pressure (mmHg), age-adjusted percentile norm, clinical guidance recommendations.

### Biological Age Calculator
- **URL**: https://healthcalc.app/biological-age-calculator/
- **Description**: Estimates biological rate of aging and functional physiological age.
- **Formulas**: Multi-factorial modifiable lifestyle risk model (Fitzgerald et al. 2021) + Levine PhenoAge algorithm (2018, NHANES III/IV) with 9 blood biomarkers.
- **Inputs**: Chronological age, exercise minutes/week, sleep quality, smoking status, alcohol consumption, diet quality index, stress level, BMI. Optional blood markers: albumin, creatinine, glucose, hs-CRP, lymphocyte %, MCV, RDW, alkaline phosphatase, WBC.
- **Outputs**: Estimated biological age, age delta (younger/older than calendar age), system age breakdown (Metabolic, Cardiovascular, Immune, Cellular), highest-leverage longevity action plan.

### HRV Calculator
- **URL**: https://healthcalc.app/hrv-calculator/
- **Description**: Analyzes Heart Rate Variability metrics from wearables (Oura, WHOOP, Apple Watch, Garmin).
- **Formulas**: Age and sex population norm percentiles for rMSSD (ms) and SDNN (ms) based on Shaffer & Ginsberg (2017).
- **Inputs**: Metric type (rMSSD or SDNN), HRV value in milliseconds, age, biological sex.
- **Outputs**: Age-matched percentile score, autonomic nervous system balance rating (Parasympathetic recovery vs Sympathetic stress), recovery readiness classification, HRV optimization guide.

### Sleep Calculator
- **URL**: https://healthcalc.app/sleep-calculator/
- **Description**: Optimizes sleep and wake times around natural ultradian 90-minute REM/NREM sleep cycles.
- **Formulas**: 90-minute sleep cycle equation: Wake Time = Bedtime + (N × 90 min) + Sleep Latency.
- **Inputs**: Target wake-up time OR current bedtime, custom sleep latency (average 15 minutes, or 5 to 45 min).
- **Outputs**: Recommended bedtimes or wake times for 6 cycles (9 hrs - optimal), 5 cycles (7.5 hrs - recommended), 4 cycles (6 hrs - acceptable), 3 cycles (4.5 hrs - minimum), REM cycle timeline.

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## 6. Pregnancy & Family Calculators

### Pregnancy Due Date Calculator
- **URL**: https://healthcalc.app/pregnancy-due-date-calculator/
- **Description**: Calculates estimated date of delivery (EDD), gestational age, and trimester progress.
- **Formulas**: Naegele's rule (LMP + 280 days), adjusted cycle length formula, Conception date (+266 days), IVF day-3/day-5 embryo transfer formula, Ultrasound crown-rump length (CRL).
- **Inputs**: Calculation method (First Day of Last Period, Conception Date, IVF Transfer, Ultrasound CRL), cycle length (default 28 days).
- **Outputs**: Estimated due date, current gestational age (weeks + days), current trimester, days remaining, due date probability window, weekly fruit/object fetal size comparison.

### Ovulation Calculator
- **URL**: https://healthcalc.app/ovulation-calculator/
- **Description**: Predicts fertile window, peak fertility days, and ovulation timing.
- **Formulas**: Ogino-Knaus rhythm method (Ovulation = Cycle Length - 14 days), fertile window = Ovulation - 5 days to Ovulation + 1 day.
- **Inputs**: First day of last menstrual period, average menstrual cycle length (21-45 days), optional luteal phase length (default 14 days).
- **Outputs**: Predicted ovulation day, 6-day fertile window, peak fertility days (O-2, O-1, Ovulation), next expected period date, 3-month fertility calendar forecast.

### Pediatric Growth Calculator
- **URL**: https://healthcalc.app/pediatric-growth-calculator/
- **Description**: Infant and child percentile tracker for physical growth.
- **Formulas**: WHO Child Growth Standards (ages 0-24 months), CDC Growth Charts (ages 2-20 years) using Cole LMS method: Z = [((X/M)^L) - 1] / (L × S).
- **Inputs**: Child's age (years + months or exact birthdate), biological sex, height/length, weight, optional head circumference.
- **Outputs**: Height-for-age percentile & Z-score, Weight-for-age percentile & Z-score, Weight-for-length / BMI-for-age percentile, WHO/CDC growth chart curve plotting.

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## 7. Nutrition & Hydration Calculators

### Protein Calculator
- **URL**: https://healthcalc.app/protein-calculator/
- **Description**: Calculates daily protein needs in grams based on body weight, physical activity, body composition, and specialized health goals.
- **Formulas**: Morton et al. (2018) meta-analysis (1.6 - 2.2 g/kg for resistance training), RDA baseline (0.8 g/kg), GLP-1 weight loss preservation guideline (1.5 - 2.0 g/kg), Helms bodybuilding prep (2.3 - 3.1 g/kg LBM).
- **Inputs**: Weight, height, activity level, primary goal (Sedentary/RDA, Active Lifestyle, Muscle Gain, Fat Loss, GLP-1 Medication, Plant-Based Athlete), optional body fat %.
- **Outputs**: Total daily protein target (g/day), grams per pound / kg, per-meal distribution (3 to 5 meals), real-food protein equivalents (chicken breast, eggs, tofu, Greek yogurt, salmon).

### Water Intake Calculator
- **URL**: https://healthcalc.app/water-intake-calculator/
- **Description**: Calculates customized daily hydration requirements.
- **Formulas**: Baseline 35 ml/kg body weight + 500-1000 ml per hour of intense exercise + 250-500 ml for hot/arid climates.
- **Inputs**: Weight, sex, daily exercise duration and intensity, ambient climate (Normal, Hot, Very Hot/Humid).
- **Outputs**: Total daily water intake in liters, fluid ounces, and 8oz glasses; hourly 8-interval hydration schedule.

### Water Weight Cut Calculator
- **URL**: https://healthcalc.app/water-weight-cut-calculator/
- **Description**: Fight-week acute weight cut and rehydration protocol designer for combat sports athletes.
- **Formulas**: Acute water loading / flushing renal response curve, low-residue gut cut calculation (1.5-2.0% body mass), safe acute fluid dehydration boundaries (MMA 24-hr max 8-10%, Wrestling/Powerlifting 2-hr max 4-5%).
- **Inputs**: Walk-around current weight, target weight class limit, weigh-in format (MMA 24-hour day-before vs Wrestling 2-hour same-day), body fat %.
- **Outputs**: Total weight to cut, feasibility & safety rating (Safe, Challenging, Dangerous), 6-day water loading schedule (Gallons/Liters per day), sodium loading/tapering plan, gut flush protocol, sweating session strategy, post-weigh-in electrolyte and glycogen rehydration timeline.