CalcVitalsHealth calculators with the method on the page
Every calculator here shows the published formula it uses and works an example in plain sight — so you can check the number, not just trust it. 48 free tools for body, food, pregnancy and training. Nothing to sign up for, and your figures never leave your browser.
Most used
BMI
Your body mass index, its category, and the healthy weight range for your height.
⚡TDEE
Your real daily calorie burn — BMR × activity, all five activity levels shown.
🍽️Calorie Calculator
Eat this much to maintain, lose or gain — targets for five goal speeds.
🥗Macro Calculator
Your calories split into grams of protein, carbs and fat — four proven splits.
👶Due Date
LMP + 280 days: your estimated due date, current week and trimester dates.
🌸Ovulation Calculator
Your likely ovulation date — counted back 14 days from your next period.
⏱️Pace Calculator
Distance + time → pace per km and mile, speed, and finish-time projections.
Body & Weight
BMI
Your body mass index, its category, and the healthy weight range for your height.
📊Body Fat Percentage
Body fat % from tape measurements (US Navy method) or from your BMI.
🎯Ideal Weight
Ideal weight by Devine, Robinson, Miller and Hamwi — plus the healthy BMI range.
💪Lean Body Mass
Lean body mass by the Boer formula: the weight of muscle, bone, organs and water.
📏Waist-to-Height Ratio
Waist ÷ height. The rule: your waist should measure less than half your height.
🧍Body Surface Area
Your skin's total area in m² — the figure used to dose medicines and assess burns.
✅Healthy Weight Range
The full healthy weight band for your height — plus every BMI threshold in kilos.
🔢BMI Prime
Your BMI as a fraction of the 25 limit — 0.86 is mid-healthy, 1.00 is the line.
🩺Adjusted Body Weight
IBW + 40% of the difference — the dosing weight used when actual weight overstates need.
📐Ponderal Index
Weight ÷ height³. Like BMI, but fairer to the very tall and very short.
⭕Waist Circumference Risk
Waist size vs the WHO risk cut-offs — the simplest abdominal-fat warning there is.
Calories & Nutrition
BMR
The calories you burn doing absolutely nothing, by the Mifflin-St Jeor equation.
⚡TDEE
Your real daily calorie burn — BMR × activity, all five activity levels shown.
🍽️Calorie Calculator
Eat this much to maintain, lose or gain — targets for five goal speeds.
📉Calorie Deficit
Pick a daily deficit and a goal weight — get the date you arrive.
🥗Macro Calculator
Your calories split into grams of protein, carbs and fat — four proven splits.
🥩Protein Calculator
Grams of protein per day for your weight and goal — sedentary to dieting athlete.
🍞Carb Calculator
Carb grams per day at your calories and chosen percentage — from keto to endurance.
🥑Fat Intake Calculator
Fat grams per day at your calorie level — plus the saturated-fat ceiling, in grams.
💧Water Intake Calculator
How much water a day by two methods, in litres, ounces and glasses.
🏃Calories Burned
Energy cost of 14 activities by your weight and minutes — MET-based, the research standard.
🗓️Weight Loss Projector
Enter what you will actually eat — see the date your goal weight arrives.
🧂Sodium Tracker
Total the sodium in what you ate — see it against the 2,300 mg and 1,500 mg lines.
☕Caffeine Half-Life
Caffeine remaining in your system now and at bedtime — the 5-hour half-life, visualised in numbers.
Pregnancy & Fertility
Due Date
LMP + 280 days: your estimated due date, current week and trimester dates.
🤰Pregnancy Week
Enter your last period — get your exact week and day of pregnancy today.
🌸Ovulation Calculator
Your likely ovulation date — counted back 14 days from your next period.
🌼Fertile Window
The six days conception is possible, with the two best days highlighted.
📅Period Calculator
Your next three period start dates, end dates and the ovulation days between.
💫Conception Calculator
Work backwards from a due date, or forwards from a period, to the likely conception day.
📈Pregnancy Weight Gain
How much to gain, by your starting BMI — total range and the expected range at your week.
🛡️Safe Period Calculator
The calendar method's 'safer' days — and its real failure rates, in the open.
🗓️Trimester Calculator
When each trimester starts and ends for your pregnancy, and where you are now.
Fitness, Running & Sleep
Pace Calculator
Distance + time → pace per km and mile, speed, and finish-time projections.
🏁Race Predictor
One race result in — predicted times for every classic distance out.
📋Split Planner
Your goal time as a pacing plan — even, negative-split or positive-split strategy.
🏋️One Rep Max
Your 1RM from any working set — plus the load for every training percentage.
🫁VO2 Max
Aerobic fitness from a 12-minute run or a 1-mile walk — no laboratory needed.
❤️Target Heart Rate
Personal training zones from max HR and resting HR — the Karvonen method.
💓Max Heart Rate
Your estimated max HR four ways — see the spread before you build zones on it.
👟Steps to Miles
Steps × stride = distance. See your step count in miles, km and walking time.
👣Steps to Calories
What your steps actually burned: distance-based, weighted by your body mass.
🏃♂️Running Calories
Running's energy cost by distance and weight — about 1 kcal per kg per km.
😴Sleep Cycle Calculator
Bedtimes and wake times in complete 90-minute cycles, so you surface in light sleep.
🍺BAC Calculator
Estimated blood alcohol now, and the hours until it clears. Only time lowers it.
💗Resting Heart Rate
Your resting heart rate against the age-and-sex tables: athlete to poor, honestly placed.
🎽Training Pace Zones
One race result → your easy, marathon, threshold, interval and repetition paces.
💦Sweat Rate
Weigh, train, weigh: your personal sweat rate and your rehydration target.
Why the formula is printed on every page
Health numbers get quoted at people constantly — a BMI category, a calorie target, a due date — usually with no way to see where the figure came from. These pages work the other way: the formula is named, the inputs are yours, and an example is worked in the open. The results are population averages from published research, useful for orientation and planning — and they are education, not medical advice. For anything that changes a decision about your health, your doctor is the right calculator.