NutriFit calculators
Free tools for nutrition, body composition and laboratory indices. Find formulas, sources and limitations alongside each result.
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Lab tests and metabolic health
Indices derived from blood work: insulin resistance, lipids, kidneys, liver, iron, vitamin D, hormones. Formulas from clinical guidelines with reference ranges.
Nutrient deficiency risk screening
Mark the lifestyle and diet factors that apply to you and see which nutrient deficiencies are likely and which laboratory tests confirm them.
- Twelve risk factors from NIH ODS and EFSA guidance
- Risk scores across nine nutrients
- A laboratory marker to verify each nutrient
HOMA-IR Calculator: Insulin Resistance Index
HOMA-IR, HOMA-β and QUICKI from fasting glucose and insulin: insulin resistance and beta-cell function with reference ranges and interpretation.
- HOMA-IR, HOMA-β and QUICKI in one calculation
- Units mmol/L ↔ mg/dL, µIU/mL ↔ pmol/L
- Sources and interpretation limits
TyG Index Calculator (Triglycerides × Glucose)
TyG index and its derivatives TyG-BMI and TyG-WC: insulin resistance and cardiometabolic risk from fasting triglycerides and glucose — no insulin assay needed.
- TyG, TyG-BMI and TyG-WC in one calculation
- No insulin assay — standard chemistry only
- Risk cut-offs from meta-analyses with sources
Lipid Panel Calculator: LDL, non-HDL and Atherogenic Indices
Calculated LDL by two methods, non-HDL, remnant cholesterol and five atherogenic indices from a standard lipid panel — with ESC/EAS target values.
- LDL by Friedewald and the Sampson equation (NIH 2020)
- non-HDL, remnant cholesterol, AIP, Castelli, atherogenic coefficient
- Units mmol/L ↔ mg/dL and ESC/EAS categories
eGFR Calculator (CKD-EPI 2021)
Estimated GFR by CKD-EPI 2021 (creatinine, optionally cystatin C), Cockcroft–Gault creatinine clearance and KDIGO CKD stage — with µmol/L and mg/dL conversion.
- CKD-EPI 2021 by creatinine and by creatinine + cystatin C
- Cockcroft–Gault creatinine clearance for drug dosing
- KDIGO CKD stages G1–G5 with explanations
HbA1c ↔ Average Glucose (eAG) Converter
HbA1c to 3-month average glycemia by the ADAG formula, reverse calculation and % ↔ mmol/mol conversion with ADA categories.
- HbA1c → average glucose in mmol/L and mg/dL
- Reverse: average glucose → expected HbA1c
- NGSP (%) ↔ IFCC (mmol/mol) conversion and ADA categories
Lab Unit Converter
Conversion of 33 lab analytes between SI (mmol/L, µmol/L, nmol/L, pmol/L) and conventional units (mg/dL, ng/mL, pg/mL) by molar mass.
- 33 analytes: chemistry, hormones, vitamins, trace elements
- Two-way conversion at report precision
- Factor table with sources
Vitamin D: van Groningen model estimate
25(OH)D in two unit systems and a weight-based research estimate. No automatic treatment schedule.
- Named research formula
- Explicit limits of applicability
- Conversion between nmol/L and ng/mL
Iron Deficiency Calculator: TSAT, Ferritin and Ganzoni Deficit
TSAT, a CRP-aware ferritin reference threshold and the arithmetic Ganzoni model. Biomarker patterns are not diagnoses.
- TSAT from iron and TIBC or transferrin
- Ferritin threshold adjusted for inflammation (WHO 2020)
- Descriptive biomarker patterns and the Ganzoni model
PhenoAge Biological Age Calculator (Levine)
A research estimate using nine biomarkers and age. The result does not predict individual life expectancy.
- 9 biomarkers from a standard CBC and chemistry panel
- PhenoAge estimate and difference from chronological age
- Original Levine 2018 coefficients in SI units
FIB-4 and APRI Calculator: Liver Fibrosis Indices
FIB-4 and APRI from age, AST, ALT and platelets, with thresholds and limitations for discussion with a clinician.
- FIB-4 with age-adjusted EASL 2021 cut-offs
- APRI with an adjustable AST upper limit of normal
- Algorithm: when elastography and a hepatologist are needed
Free Testosterone Calculator (Vermeulen)
Free and bioavailable testosterone fractions from the Vermeulen 1999 binding model. Results require method-specific reference intervals and clinical context.
- Free and bioavailable testosterone by Vermeulen
- Units nmol/L ↔ ng/dL, pg/mL and fraction percentages
- Reference-interval guidance and calculation limitations
Anion Gap and Delta Ratio Calculator
Anion gap corrected for albumin (Figge) and the ΔAG/ΔHCO₃ delta ratio to distinguish high- and normal-anion-gap acidosis.
- Anion gap from Na, Cl and HCO₃
- Albumin correction per Figge
- Delta ratio for mixed disorders
Albumin-Corrected Calcium Calculator
Educational calculation of albumin-adjusted total calcium using the simplified Payne formula. It does not measure ionized calcium or determine treatment.
- Payne correction in mmol/L and mg/dL
- Albumin in g/L or g/dL
- Warning when ionized calcium is needed
Fitness and exercise physiology
Strength benchmarks, heart-rate zones, endurance, body composition and anthropometry — the toolkit of a coach and a sports physician.
Body composition calculator
Estimates body fat percentage from circumferences, calculates fat and lean mass and body mass index.
- Body fat from circumferences, no equipment needed
- Fat mass and lean mass in kilograms
- BMI with the WHO category
1RM Calculator (One-Rep Max)
Calculates the maximum load an athlete can lift for a single repetition without the injury risk of direct 1RM testing.
- Simultaneous calculation across 5 validated formulas (Epley, Brzycki, Lombardi, Wathan, Mayhew)
- Complete training percentage chart from 50% to 100% of 1RM with estimated repetition targets
- Practical guidelines for bench press, squat, and deadlift with RPE scale adjustment
Heart Rate Training Zones Calculator
Calculates individual target heart rate zones accounting for both maximum heart rate and resting pulse (Heart Rate Reserve method).
- Karvonen formula personalized by individual resting morning heart rate
- Selectable HRmax equations: Tanaka, Haskell-Fox, or measured laboratory maximum
- Detailed physiological descriptions, fuel substrate utilization, and talk-test cues for each of the 5 zones
VO2 Max Calculator (Cardiorespiratory Fitness)
Evaluates aerobic power and cardiorespiratory fitness based on validated field protocols without specialized laboratory gas analysis equipment.
- 3 validated protocols: Cooper run test, Rockport fitness walking test, and non-exercise Uth heart rate ratio
- Official Cooper Institute age- and sex-adjusted aerobic fitness norms (from Very Poor to Superior)
- Estimated race pace projections for 5K and 10K running events based on calculated aerobic ceiling
FFMI Calculator (Fat-Free Mass Index)
Determines lean muscular mass relative to height, distinguishing genuine hypertrophy from body fat accumulation.
- Calculation of both baseline and height-normalized FFMI (standardized to 1.80 m)
- Objective assessment of proximity to the natural genetic muscular ceiling (Kouri index 25.0)
- Accurate calculation of absolute lean tissue and fat mass in kilograms
Katch-McArdle BMR & TDEE Calculator
Calculates basal metabolic rate (BMR) and total daily energy expenditure (TDEE) based strictly on lean muscle mass rather than total scale weight.
- Most accurate energy expenditure estimation for athletes, bodybuilders, and fitness enthusiasts
- Parallel calculation across Katch-McArdle, Cunningham (1991), and Mifflin-St Jeor models
- Direct calorie discrepancy comparison between lean mass and total weight equations
Ideal Body Weight Calculator (IBW & AdjBW)
Calculates reference body weight according to recognized clinical equations and determines Adjusted Body Weight (AdjBW) for clinical nutrition and medicine.
- Direct comparison across 4 classic clinical formulas: Devine, Robinson, Miller, and Hamwi
- Calculation of Adjusted Body Weight (AdjBW) for accurate nutritional and clinical dosing in overweight individuals
- World Health Organization (WHO) healthy weight reference range (BMI 18.5–24.9 kg/m²)
Waist Anthropometric Index Calculator (WHtR, WHR, VAI)
Evaluates body fat distribution, visceral adiposity, and cardiometabolic risk far more accurately than standard BMI.
- Calculation of the Waist-to-Height Ratio (WHtR) with the universal 'Ashwell Rule of Thumb' (< 0.50)
- Evaluation of fat distribution patterns according to WHO standards (Android vs. Gynoid)
- Clinical Visceral Adiposity Index (VAI) incorporating triglycerides and HDL cholesterol
Sweat Rate & Hydration Calculator
Determines individual sweat loss rate and calculates personalized post-exercise fluid and electrolyte replacement needs.
- Exact calculation of sweat rate in liters per hour adjusted for workout duration and fluid consumed
- Assessment of percentage dehydration and its projected physiological impairment on athletic performance
- Personalized post-exercise rehydration volume based on the clinical 125–150% fluid replacement protocol
Maximum Muscular Potential Calculator (Casey Butt & Berkhan)
Estimates the maximum drug-free lean body mass and muscular circumferences (chest, arms, thighs) achievable without anabolic pharmacology.
- Casey Butt scientific skeletal model based on wrist and ankle frame thickness
- Martin Berkhan (Leangains) contest weight benchmark for 4–6% body fat
- Maximum natural circumference limits for chest, biceps, forearms, thighs, and calves
Powerlifting Coefficients Calculator (DOTS, Wilks, IPF GL)
Evaluates and benchmarks relative strength in powerlifting (squat, bench press, deadlift) across diverse body weights and sexes using DOTS, Wilks, and IPF GL Points.
- Contemporary international standard DOTS score (USAPL, WRPF, ACAA)
- Classic Wilks formula for historical performance comparisons
- Official International Powerlifting Federation (IPF) GL Points for Raw and Equipped
Nutrition and dietetics
Energy, macro- and micronutrients, water, salt, fiber, omega-3 and glycemic load — every target with its source.
Daily calorie needs calculator (TDEE)
Calculates basal metabolic rate and total daily energy expenditure, plus calorie targets for losing, maintaining and gaining weight.
- Basal metabolic rate and total daily energy expenditure
- Calorie targets for loss, maintenance and gain
- Five activity levels with explicit factors
Macronutrient calculator
Splits a daily calorie target into protein, fat and carbohydrates based on body weight and goal — in grams, calories and percentages.
- Protein, fat and carbohydrates in grams, calories and percentages
- Ranges for protein and fat rather than a single number
- Three goals: loss, maintenance and gain
Water intake calculator
Calculates daily fluid needs from body weight with adjustments for physical activity and hot climate.
- Fluid needs from body weight and age
- Adjustments for training and hot climate
- Drink-only volume and an equivalent in glasses
Glycemic load calculator
Calculates the glycemic load of a serving from its glycemic index and carbohydrate content — a measure that reflects the real glucose response better than the index alone.
- Glycemic load of any serving size
- Reference glycemic index values for common foods
- Index and load categories with explicit thresholds
Protein Intake Calculator (ISSN & ESPEN)
Determines individualized daily protein targets based on fitness goals, dietary pattern, and muscle protein synthesis (MPS) thresholds.
- Differentiated clinical targets across 8 sports and health goals
- Renal protection via Adjusted Body Weight (AdjBW) for BMI > 28
- Per-meal protein pacing optimized for muscle protein synthesis (MPS)
Dietary Fiber Intake Calculator (WHO & EFSA)
Quantifies daily soluble and insoluble dietary fiber requirements to support gut microbiome diversity, optimize lipid profiles, and maintain healthy transit time.
- Differentiates between soluble prebiotic fibers (pectins, beta-glucans) and insoluble bulking fibers
- Hydration requirement calculator to prevent constipation from supplemental fiber
- Tailored clinical recommendations for irritable bowel syndrome (IBS / low-FODMAP)
Omega-3 Intake & Index Calculator (EPA + DHA)
Determines therapeutic and maintenance dosages of active EPA and DHA fatty acids according to clinical indications and laboratory biomarkers.
- Calculates active EPA + DHA content rather than gross fish oil mass
- Targeted EPA:DHA ratios tailored for brain, cardiovascular, or joint health
- Erythrocyte membrane Omega-3 Index lab test stratification
Sodium-Potassium Balance & Salt Calculator (Na:K)
Analyzes electrolyte balance between sodium and potassium, converting milligrams of sodium into dietary salt and identifying hypertension risk.
- Precise molar ratio calculation based on elemental atomic weights
- Instant conversion of dietary sodium to grams of table salt (NaCl)
- DASH-aligned thresholds for individuals with elevated blood pressure
Alcohol Clearance & Sobriety Calculator (Widmark)
Calculates peak and current blood alcohol concentration (BAC in ‰), precise time to complete sobriety, and empty caloric load from ethanol.
- Forensic Widmark pharmacokinetic equation with stomach fullness factor
- Time projection to reach zero BAC in blood and breath
- Quantification of empty ethanol energy (7.1 kcal/g)
Caffeine Clearance & Sleep Timing Calculator
Simulates caffeine pharmacokinetics, biological half-life, and remaining bedtime adenosine blockade to safeguard deep slow-wave sleep.
- Pharmacokinetic decay modeling adjusted for smoking, oral contraceptives, and pregnancy
- Bedtime adenosine receptor blockade risk assessment (< 35 mg safe threshold)
- Extensive database of espresso, drip coffee, energy drinks, tea, and pre-workouts
Dynamic Weight Loss Forecast Calculator (Kevin Hall Model)
Generates a realistic, non-linear weight loss trajectory using the NIH/NIDDK model of Kevin Hall, accounting for adaptive thermogenesis and body composition changes.
- Official biophysical model from the National Institutes of Health (NIH/NIDDK)
- Direct comparison of dynamic metabolic curve against outdated static linear rules
- Body composition forecasting: partitioning of fat mass versus lean tissue retention
Lifestyle and prevention
Sleep, caffeine, alcohol, weight forecasts and validated risk screenings — what shapes health between doctor visits.
Health & Nutrition Balance Wheel
Interactive radar chart of 8 health and lifestyle dimensions. Identifies bottlenecks (Liebig's Law of the Minimum) and links deficits to NutriFit tools.
- Interactive 8-pillar health radar chart
- Automatic Liebig bottleneck identification
- Direct integration with NutriFit calculators and food tracking
Sleep Cycles Calculator
A sleep timing tool based on 90-minute ultradian cycles (slow-wave and REM sleep phases) and average sleep onset latency.
- Calculates bedtime for a target morning wake-up time
- Calculates wake-up time if you go to bed right now
- Accounts for individual sleep onset time, plus nap-timing tips
FINDRISC Diabetes Risk Score
An internationally recognized WHO and IDF questionnaire for early screening of undiagnosed diabetes and estimating the 10-year risk of developing type 2 diabetes.
- Instant assessment of 10-year diabetes risk without invasive procedures
- Accounts for ethnic and clinical waist circumference thresholds
- Personalized clinical recommendations for diabetes prevention
Psychology and eating behavior
Free validated screening questionnaires for depression, anxiety and eating disorders. A score is a reason to talk to a professional, not a diagnosis.
Dutch Eating Behavior Questionnaire (DEBQ)
A classic validated psychological instrument designed to assess three primary eating behavior patterns: restrained eating, emotional eating, and external eating.
- Complete 33-item validated instrument with granular scoring across 3 subscales
- Comparison against standardized population clinical reference norms
- Personalized evidence-based recommendations for each identified eating profile
Patient Health Questionnaire-9 (PHQ-9 Depression)
The international gold standard for primary depression screening and symptom severity assessment based on DSM-5 clinical criteria.
- Official 9-item DSM-5 validated clinical questionnaire
- Instant severity grading with evidence-based action steps
- Automated identification of critical crisis risk factors
Generalized Anxiety Disorder 7-Item Scale (GAD-7)
An international clinical screening instrument designed to rapidly evaluate the severity of generalized anxiety and emotional tension.
- Concise and precise 7-item psychometric assessment
- High diagnostic sensitivity and specificity for generalized anxiety
- Practical, evidence-grounded stress reduction and self-regulation recommendations
Perceived Stress Scale (PSS-10)
The classic psychological scale by Sheldon Cohen designed to measure the degree to which situations in one's life are appraised as unpredictable, uncontrollable, and overloading.
- 10 scientifically validated items with bidirectional psychometric scoring
- Evaluation of the equilibrium between perceived demands and coping resources
- Tailored recommendations for stress mitigation and burnout prevention
Insomnia Severity Index (ISI)
A concise 7-item clinical instrument designed to evaluate the nature, severity, and daytime impact of insomnia symptoms.
- Comprehensive evaluation of sleep latency, midnight awakenings, and early terminal waking
- Assessment of perceived daytime functional impairment and cognitive fatigue
- Evidence-grounded sleep hygiene rules and circadian synchronization guidelines
SCOFF Eating Disorder Screening Questionnaire
An internationally recognized 5-question clinical screening tool designed to identify the risk of eating disorders (anorexia nervosa and bulimia nervosa).
- Rapid, evidence-based screening completed in under 1 minute
- High clinical sensitivity (100%) and specificity (87.5%)
- Clear referral pathways and supportive clinical recommendations
Intuitive Eating Scale-2 (IES-2)
A scientifically validated 23-item psychometric instrument by Tracy Tylka designed to measure adaptive, intuitive relationships with food and body signals.
- Complete validated 23-item IES-2 instrument with 4 comprehensive subscales
- Evaluation of visceral body cue trust, mindful eating, and diet mentality
- Targeted milestones for exiting chronic restrictive diet cycles
Yale Food Addiction Scale mYFAS 2.0
An adapted scientific questionnaire developed at Yale University to assess symptoms of addictive eating behavior toward highly palatable, ultra-processed foods.
- Official brief version of mYFAS 2.0
- Alignment with DSM-5 diagnostic criteria for substance-related disorders
- Assessment of clinical distress and functional impairment
Eating Behavior Diagnostic Wizard
An integrated diagnostic wizard by NutriFit synthesizing leading validated scales to identify your core eating behavior archetype and personalized action plan.
- Comprehensive profile combining 4 evidence-based psychological scales
- Identification of core eating archetypes and relapse triggers
- Step-by-step personalized strategy for clients and nutritionists
This calculation is for reference only and is not medical advice, a diagnosis or a prescription. If you have a medical condition, are pregnant, take medication or have any doubts, discuss the result with a physician or a qualified nutrition professional.
What next
Formula breakdowns, biomarker reference ranges and nutrition articles with cited sources are in the NutriFit knowledge base.
Go to the knowledge base