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Calculators/Health & Fitness

Health & Fitness calculators

Body composition, training load and sports performance, using published clinical and sports-science formulas.

Health

Body composition, energy needs, training load and cycle tracking, using the standard published clinical and sports-science formulas.

Body mass index (BMI)Weight relative to height, with the WHO category.BMR: basal metabolic rateEnergy burned at complete rest (Mifflin-St Jeor).TDEE: daily calorie needsBMR scaled by how active you are.Weight change timelineHow long a given calorie gap takes to shift a target.Body fat percentage (US Navy)Tape-measure estimate of body composition.Ideal body weightFour classic clinical formulas side by side.Macronutrient splitGrams of protein, carbs and fat for a calorie target.Daily water intakeBaseline fluid target adjusted for exercise and heat.Calories burned (MET)Energy cost of an activity from its metabolic equivalent.Heart rate training zonesKarvonen zones from resting and maximum heart rate.VO₂ max (Cooper test)Aerobic fitness from a 12-minute run.One-rep maxStrength ceiling estimated from a submaximal set.Running pace & finish timeConverts between pace, speed and race time.Pregnancy due dateEstimated delivery date from the last period (Naegele’s rule).Body surface areaUsed for drug dosing and cardiac index.Waist-to-hip & waist-to-heightFat distribution measures that track health risk.Ovulation & fertile windowLikely fertile days across a cycle.Sleep cycle timingWake times that fall between 90-minute sleep cycles.Anion gapUnmeasured ions in the blood, a first step in narrowing the cause of a metabolic acidosis.Corrected calcium for albuminAdjusts a total calcium reading for a low albumin level, using the Payne formula.Blood alcohol content (Widmark formula)Rough estimate of blood alcohol content from drinks consumed, body weight and time elapsed.Estimated average glucose from A1CConverts an HbA1c percentage into an average blood glucose reading (ADAG study formula).Corrected QT interval (QTc)Heart-rate-adjusted QT interval from an ECG reading, using the Bazett and Fridericia formulas.Creatinine clearance (Cockcroft-Gault)Estimated kidney filtration rate from age, weight and serum creatinine.Lean body mass (Boer formula)Fat-free body mass estimated from height and weight.Mean arterial pressure (MAP)Average pressure driving blood flow through the body over one heartbeat cycle.Total body water (Watson formula)Estimated volume of water in the body from age, height and weight.Fat-free mass index (FFMI)Muscularity measure that adjusts fat-free mass for height, comparable across body sizes.Smoking pack-yearsCumulative smoking exposure used in clinical risk screening.LDL cholesterol (Friedewald equation)Estimated LDL cholesterol from a standard lipid panel.Total cholesterol to HDL ratioA single number summarizing cardiovascular risk from a lipid panel.Daily protein intakeProtein target range based on body weight and activity level.Daily fiber intake targetRecommended dietary fiber based on total calorie intake.A Body Shape Index (ABSI)Waist circumference adjusted for height and BMI, an alternative to the waist-to-height ratio.Relative fat mass (RFM)Body fat percentage estimated from height and waist circumference (Woolcott-Bernstein).Shock indexHeart rate divided by systolic blood pressure, a quick marker of circulatory stress.Rate pressure productHeart rate times systolic blood pressure, an index of how hard the heart is working.HOMA-IR (insulin resistance)Estimated insulin resistance from fasting glucose and fasting insulin levels.Calculated serum osmolalityEstimates blood osmolality from a basic metabolic panel, plus the osmolal gap.Corrected sodium for hyperglycemiaAdjusts a measured sodium reading for high blood glucose, using the Katz and Hillier formulas.Delta ratio (delta gap)Compares the rise in anion gap to the fall in bicarbonate, to spot a mixed acid-base disorder.BUN-to-creatinine ratioCompares blood urea nitrogen to creatinine, used to help distinguish causes of kidney injury.AST-to-ALT ratio (De Ritis ratio)Compares two liver enzymes, sometimes used to point toward a pattern of liver injury.Albumin-to-globulin ratioSplits total blood protein into albumin and globulin and compares the two.Transferrin saturation (TSAT)The share of iron-carrying protein that is actually loaded with iron.Mentzer indexScreens a routine blood count for thalassemia trait versus iron-deficiency anemia.FEV1/FVC ratioShare of lung capacity exhaled in the first second of a forced breath, from spirometry.Minute ventilationThe total volume of air moved in and out of the lungs in one minute.Estimated height from knee heightStanding height for a patient who cannot be measured directly (Chumlea equations).Adjusted body weightBlends actual and ideal body weight, a middle-ground figure used for larger patients.Ponderal indexA leanness measure like BMI, but using height cubed for consistency at any height.Body roundness index (BRI)Estimates body shape and visceral fat from waist and height, an alternative to BMI.Osteoporosis risk score (OST index)A quick screening score from age and weight, flagging who might need bone density testing.Pregnancy weight gain guidelineRecommended weight gain for a singleton pregnancy, by pre-pregnancy BMI (IOM guidelines).Gestational age from crown-rump lengthDates an early pregnancy from a first-trimester ultrasound measurement.Fundal height gestational age (McDonald’s rule)Between 20 and 36 weeks, fundal height in centimetres roughly tracks gestational age.Glycemic loadCombines a food’s glycemic index with the actual carbohydrate in a serving.Net carbsCarbohydrate grams likely to affect blood sugar, after subtracting fibre and sugar alcohols.Mid-parental height predictionPredicted adult height for a child from both parents heights (Tanner method).Drug elimination by half-lifeFraction of a substance remaining or cleared after a given time, from its half-life.Predicted vital capacityExpected lung vital capacity for a healthy adult, from height, age and sex.Free water deficitEstimated water needed to correct a high serum sodium (hypernatraemia).Urine anion gapUrinary electrolyte gap that helps distinguish causes of a normal anion-gap metabolic acidosis.Fractional excretion of sodium (FeNa)Compares urine and plasma sodium and creatinine to help classify acute kidney injury.Urine protein-to-creatinine ratioEstimates 24-hour urinary protein loss from a single spot urine sample.MCH & MCHC (red cell indices)Average haemoglobin content and concentration per red blood cell, from a full blood count.Absolute neutrophil count (ANC)Total mature and immature neutrophils in circulation, used to gauge infection risk.PSA densityPSA level adjusted for prostate size, used alongside other tests to gauge cancer risk.RMR from lean mass (Katch-McArdle)Resting metabolic rate estimated from lean body mass rather than total weight.PaO₂/FiO₂ ratio (Horowitz index)Oxygenation index used to gauge the severity of acute respiratory failure.Alveolar-arterial (A-a) gradientGap between calculated and measured arterial oxygen, a clue to the cause of hypoxaemia.Bolton tooth-size ratioCompares upper and lower tooth widths to flag a size mismatch before orthodontic treatment.Amplitude of accommodation (Hofstetter)Expected eye-focusing range for a given age, and the approximate near point for reading.Number needed to treat (NNT)How many patients must be treated to prevent one additional bad outcome, from two event rates.Vaccine efficacyPercentage reduction in disease risk among a vaccinated group versus an unvaccinated group.Ankle-brachial index (ABI)Peripheral artery disease screening ratio of ankle to arm blood pressure.Left ventricular ejection fractionPercentage of blood pumped out of the left ventricle with each heartbeat.Cardiac output & cardiac indexBlood pumped by the heart each minute, scaled to body size.Cerebral perfusion pressure (CPP)Net pressure driving blood flow to the brain, from blood pressure and intracranial pressure.Lung-protective tidal volume (ARDSnet)Low tidal volume ventilation target from predicted body weight and height.Physiologic dead space (Bohr equation)Share of each breath that does not take part in gas exchange.Alcohol units (UK)UK standard units of pure alcohol in a drink, from volume and strength.Reticulocyte production index (RPI)Corrects a reticulocyte percentage for anaemia severity and cell maturation time.Albumin-to-creatinine ratio (ACR)Urine albumin relative to creatinine, a standard kidney-damage screening test.FIB-4 index (liver fibrosis)Screens for advanced liver fibrosis risk from age plus a routine liver panel and platelet count.Transtubular potassium gradient (TTKG)Estimates how well the kidney is handling potassium from paired urine and serum readings.Urea reduction ratio (URR)Percentage drop in blood urea over one haemodialysis session, a dialysis-adequacy check.Winters’ formula (expected pCO₂)Checks whether respiratory compensation for a metabolic acidosis looks appropriate.Neutrophil-to-lymphocyte ratio (NLR)A simple inflammation marker calculated from a routine blood differential.Caffeine remaining in the bodyEstimates caffeine left in your system over time using first-order elimination kinetics.Karvonen target heart rateTarget heart rate training zone from heart rate reserve, using the Karvonen formula.Body frame sizeClassifies frame size as small, medium or large from the height-to-wrist-circumference ratio.IQ percentileWhere an IQ score ranks against the population, from the normal distribution.Blood glucose unit converterConverts blood glucose readings between mmol/L and mg/dL.Adjusted age for premature babiesCorrects a premature baby’s age for weeks born early, for milestone tracking.DIY hand sanitizer recipe (WHO formula)Scales the WHO alcohol-based handrub formulations to any batch size.Safe noise exposure timeMaximum daily exposure time allowed at a given noise level, NIOSH or OSHA rules.Added sugar daily limitCompares a day’s added sugar against the AHA recommended maximum.Sleep debt trackerCumulative sleep shortfall over several nights against a target amount of sleep.Next blood donation eligibility dateEarliest date you can donate again, from your last donation and the donation type.Estimated conception dateBack-calculates a likely conception date from a due date or the start of the last period.Child blood type probabilityPossible ABO and Rh blood types of a child from both parents, classic Mendelian genetics.Baby formula daily intakeApproximate daily formula volume for a bottle-fed baby, from weight and age.US standard alcoholic drinksNumber of US standard drinks (14 g pure alcohol each) in a beverage, from volume and ABV.Baby eye color probabilityLikely eye colors for a baby from both parents’ eye colors, using a simplified genetic model.Breastfeeding extra calorie needsExtra daily calories needed while exclusively breastfeeding, on top of your baseline TDEE.Vitamin mcg to IU converterConverts vitamin A or vitamin D between micrograms (mcg) and International Units (IU).Cholesterol unit converterConverts total cholesterol, HDL, LDL or triglycerides between mg/dL and mmol/L.

Sports

Performance and scoring maths for training and competition, from gear ratios to rating systems.

Bike gear ratio & speedGear ratio, development and road speed for a given chainring, cog and cadence.Bike frame sizeRecommended frame size from inseam length, by bike type.Stride length & distance from stepsStride length from height, and a step count turned into distance.Hull speed (displacement boat)The theoretical top speed of a displacement-hull boat from its waterline length.Wilks score (powerlifting)Bodyweight-adjusted strength score for comparing lifters across weight classes.Elo rating changeHow a single result moves a player or team’s Elo rating.NFL passer ratingThe 0–158.3 quarterback rating from completions, yards, touchdowns and interceptions.Race time predictorPredicts a finish time at a new distance from a recent race result, using Riegel’s formula.Hiking time (Naismith’s rule)Estimated walking time for a hike from distance and total ascent.Bruce protocol VO₂maxEstimated maximal oxygen uptake from total time on a standard Bruce treadmill test.Magic number (pennant race)Combined wins by your team and losses by the nearest rival needed to clinch a spot.Net run rate (cricket)The run-rate differential used to separate teams level on points.E-bike rangeEstimated riding range from battery capacity and energy use per distance.Fishing reel line capacityHow much line of a new diameter fits on a reel, from a known spool capacity.Pool table room sizeMinimum room dimensions so a cue has room to swing on every shot.Swim pacePace per 100 m/yd and average speed for a swim, from distance and time.Cycling power-to-weightWatts per kilogram from your power output and body weight, with a rough training category.Golf course handicapCourse handicap for a round, from Handicap Index, Slope Rating and Course Rating.Ape indexHow your arm span compares to your height, a rough climbing-reach indicator.Bike chain lengthChain length in links for a bike from chainstay length and the largest chainring and cog.Fish weight from lengthEstimated fish weight from length and girth, or length alone, using standard angler formulas.Baseball WHIPWalks plus hits per inning pitched, the standard measure of baserunners a pitcher allows.Winning percentageWin rate for a team or player, with ties counted as half a win.Batting average (baseball or cricket)Hitting average from hits and at-bats, or runs and dismissals for cricket.Slugging percentageTotal bases per at-bat, a power-hitting measure in baseball and softball.Goalie save percentageShare of shots faced that a goalkeeper stopped, hockey or soccer.Effective field goal percentage (eFG%)Basketball shooting efficiency that weights three-pointers as worth more.Cricket bowling averageRuns conceded per wicket taken, lower is better for a bowler.Earned run average (ERA)A pitcher’s earned runs allowed per nine innings pitched, baseball or softball.Calories burned by heart rateEnergy burned during exercise from average heart rate, age, weight and sex.Vertical leap needed to dunkMinimum vertical jump required to dunk a basketball, from your standing reach and rim height.Rowing ergometer pace to wattsConverts a rowing machine 500 m split time to power output, the Concept2 formula.Triathlon total timeAdds swim, transition, bike and run splits into a total triathlon finish time.On-base percentage (OBP)How often a batter reaches base safely per plate appearance, baseball or softball.Fielding percentageShare of fielding chances handled cleanly, baseball or softball defense.Bench press one-rep maxEstimated one-rep max (1RM) bench press from a weight and rep count, using the Epley formula.NBA game scoreJohn Hollinger’s single-game performance rating from a box score line.True shooting percentageBasketball shooting efficiency that accounts for three-pointers and free throws.MET-minutes per weekWeekly physical activity volume in MET-minutes, checked against the WHO activity guideline.Goals against average (hockey)A goaltender’s goals allowed per 60 minutes of play, the standard hockey goaltending stat.Cricket batting strike rateRuns scored per 100 balls faced, the standard measure of scoring pace in cricket.