BMI Calculator
Estimate body mass index from height and weight.
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Health & Family Calculators
BMI, calories, age, height, pets, and family tools
These health and family calculators cover the practical measurements that come up across a lifetime: BMI and healthy weight ranges, daily calorie and macronutrient estimates based on your goals, exact age in years and days, height comparison across family members, and dog or cat years converted to human-age equivalents. Each tool explains the formula used, the standard it follows, and the assumptions that affect accuracy.
Health & family
Health & Nutrition Calculators
Estimate BMI, daily calorie needs, and TDEE from age, sex, height, weight, and activity level to support health and fitness goals.
Calorie Calculator
Estimate daily calorie needs from age, sex, height, weight, and activity level for any goal.
Pomodoro Timer
Focus with timed work sessions, short breaks, and long breaks.
Health & family
Age & Growth Tracking
Calculate exact age in years and days, track height milestones, and see how different people compare on a visual chart.
Age Calculator
Calculate exact age, birthday countdowns, and life milestones.
Height Comparison Tool
Compare two or more heights on a simple visual chart.
Health & family
Family & Pets
Convert dog and cat years into human-age equivalents, and split children or family members into fair groups for activities and games.
Pet Age Calculator
Convert dog or cat years into human-age equivalents.
Random Team Generator
Split names into fair teams for class, sport, or games.
Understanding Health Estimates
Body mass index is a ratio of weight to height squared (kg/m²). It is a population-level screening tool, not a diagnostic measure. A BMI between 18.5 and 24.9 is classified as healthy weight for adults, but it does not account for muscle mass, bone density, age, or fat distribution. The BMI Calculator uses the standard WHO formula and notes these limitations in the results. Use it as a starting point, not a medical assessment.
Calorie Needs and the Mifflin-St Jeor Formula
The Calorie Calculator uses the Mifflin-St Jeor equation, which is the formula most commonly recommended by dietitians for estimating basal metabolic rate. It takes age, sex, height, and weight as inputs, multiplies by an activity factor to get TDEE (total daily energy expenditure), then adjusts by a goal-based calorie offset. A deficit of 500 kcal/day produces roughly 0.5 kg of loss per week under controlled conditions — real results vary with water retention, hormonal factors, and measurement error.
How the Pet Age Conversion Works
The common "multiply by 7" rule for dog years is an oversimplification. Dogs age rapidly in their first two years, then more slowly. The Pet Age Calculator uses species- and size-specific curves based on AVMA-aligned research. A 2-year-old medium dog is approximately 24 in human years, not 14. Cat age conversion follows a different curve from dogs because cats mature at different rates in their early years.
Focused Work and the Pomodoro Technique
The Pomodoro Timer implements the time-management method developed by Francesco Cirillo, which alternates 25-minute focused work sessions with 5-minute short breaks and a longer break after four sessions. Research on focused attention suggests that sustained concentration depletes over time and that scheduled breaks improve overall output. The technique is especially useful for tasks that require sustained cognitive effort — studying, writing, and detailed analysis.
FAQ
Health & Family Calculator Questions
Short answers for readers and answer engines.
How accurate is an online BMI calculator?
For adults aged 20 and over, the BMI formula is the same worldwide (weight in kg ÷ height in m²). The calculation itself is accurate, but BMI is a limited health measure that does not account for muscle mass, fat distribution, or ethnicity-specific risk thresholds. Use it as one data point alongside other health indicators.
How many calories should I eat per day?
It depends on your age, sex, height, weight, and activity level. The Calorie Calculator estimates your TDEE using the Mifflin-St Jeor equation and adjusts it for your goal — weight loss, maintenance, or gain. Calorie needs change as weight changes, so recalculate every few weeks if you are actively managing your weight.
How are dog years converted to human years?
The Pet Age Calculator uses size- and species-adjusted conversion curves rather than the commonly cited 7× rule. A 1-year-old medium dog is roughly equivalent to 15 human years; by age 10, the equivalent is around 66. Cats follow a slightly different curve, with rapid aging in years 1–2 and a slower pace thereafter.
What is the best way to track my child's age precisely?
The Age Calculator shows exact age in years, months, days, and total days, plus a countdown to the next birthday. It handles leap years correctly and supports any date pair — useful for tracking milestones, medical appointments, and anniversary dates.