Body Mass Index (BMI) is a widely used screening tool that estimates whether a person has a healthy body weight relative to their height. It is calculated by dividing weight in kilograms by height in meters squared (kg/m²). While BMI is a useful starting point, it does not measure body fat directly and does not account for factors like muscle mass, bone density, age, or where fat is distributed in the body.
Athletes and highly muscular individuals may have a high BMI despite having very low body fat. Older adults may have a normal BMI but still carry excess body fat. For a complete picture of your health, BMI should be used alongside other assessments such as waist circumference, blood pressure, and cholesterol levels. Always consult a healthcare provider for a full evaluation.
Frequently Asked Questions
What is a healthy BMI range?
For most adults, a BMI between 18.5 and 24.9 is considered healthy. A BMI below 18.5 is classified as underweight, 25.0–29.9 as overweight, and 30.0 and above as obese. These thresholds are guidelines — individual health varies significantly within each range.
Is BMI accurate for everyone?
BMI has known limitations. It can overestimate body fat in athletes and people with high muscle mass, and underestimate it in older adults who have lost muscle. It also does not distinguish between fat stored around the abdomen (higher risk) versus other areas. The CDC and WHO both note that BMI is a screening tool, not a diagnostic one.
Does BMI differ by age or sex?
The standard BMI scale applies to adults aged 20 and older regardless of age or sex. For children and teens (ages 2–19), BMI is calculated the same way but interpreted using age- and sex-specific percentile charts, since body composition changes significantly during growth.
This calorie calculator uses the Mifflin-St Jeor equation, one of the most widely validated formulas for estimating daily caloric needs. It calculates your Basal Metabolic Rate (BMR) — the number of calories your body needs at complete rest — then multiplies it by an activity factor to estimate your Total Daily Energy Expenditure (TDEE).
Your TDEE is the number of calories you need to maintain your current weight. To lose weight at a safe rate of approximately one pound per week, aim for a deficit of 500 calories per day below your TDEE. To gain weight or build muscle, aim for a surplus of 250–500 calories above your TDEE. These are starting estimates — individual metabolism varies, and you may need to adjust based on real-world results.
Frequently Asked Questions
How many calories should I eat per day?
Daily calorie needs vary widely based on age, sex, height, weight, and activity level. General guidelines suggest 1,600–2,400 calories for adult women and 2,000–3,000 for adult men, but these are rough averages. Use the calculator above for a personalized estimate based on your specific profile.
What is the difference between BMR and TDEE?
BMR (Basal Metabolic Rate) is the number of calories your body burns at complete rest just to maintain basic functions like breathing and circulation. TDEE (Total Daily Energy Expenditure) is your BMR multiplied by an activity factor — it represents the total calories you burn in a day including exercise and daily movement.
Is it safe to eat below my BMR?
Consistently eating below your BMR is generally not recommended and can lead to muscle loss, nutrient deficiencies, fatigue, and metabolic adaptation. Most health professionals recommend keeping calorie intake above BMR and achieving weight loss through a moderate deficit from TDEE rather than extreme restriction.
The age calculator determines your exact age in years, months, and days based on your date of birth and a target date. It is useful for a wide range of purposes — from filling out official forms and calculating retirement eligibility to satisfying simple curiosity about exactly how old you are down to the day.
You can also use it to calculate the age of anything with a known start date — a business, a marriage, a building, or a historical event. Simply enter the start date as the "date of birth" and the current date or any future date as the "calculate as of" date.
Frequently Asked Questions
How is age calculated across different months?
Age calculation accounts for the varying lengths of months. When the current day is less than the birth day in the current month, the previous month is used as the reference, and the days are calculated based on the actual length of that month. This ensures accuracy even across February and months with different day counts.
What is the legal age of majority in the United States?
In the United States, the age of majority is 18 in most states, meaning a person is legally considered an adult at that age. Nebraska and Alabama set the age of majority at 19. Mississippi sets it at 21 for certain purposes. Always verify with local laws for specific legal contexts.
The pregnancy due date calculator estimates when your baby is expected to arrive based on either the first day of your last menstrual period (LMP), your known conception date, or your IVF embryo transfer date. The standard pregnancy is calculated as 280 days (40 weeks) from the first day of the last period, though full-term delivery can occur anywhere from 37 to 42 weeks.
Keep in mind that only about 5% of babies are born on their exact due date. The due date is best understood as the midpoint of a window — most births occur within two weeks before or after. Your healthcare provider may adjust your estimated due date based on ultrasound measurements, particularly in the first trimester when dating is most accurate.
Frequently Asked Questions
How accurate is an estimated due date?
Due dates calculated from the last menstrual period assume a 28-day cycle and ovulation on day 14, which is average but not universal. First-trimester ultrasound dating is considered more accurate and is typically used to confirm or adjust the LMP-based estimate. Most healthcare providers consider a due date accurate to within 1–2 weeks.
What are the three trimesters of pregnancy?
The first trimester covers weeks 1–13, the second trimester weeks 14–26, and the third trimester weeks 27–40. Each trimester brings distinct developmental milestones and different physical experiences for the mother. The second trimester is often considered the most comfortable period of pregnancy.
What is the difference between gestational age and fetal age?
Gestational age is counted from the first day of the last menstrual period and is the standard used by healthcare providers — it is typically 2 weeks longer than fetal age. Fetal age (also called embryonic age) is counted from the date of conception and represents the actual age of the embryo or fetus.