BMI Calculator
Calculate your Body Mass Index based on height and weight.
Your BMI Result
Body Fat Calculator
Estimate body fat percentage using the US Navy method.
Body Fat Result
BMR Calculator
Calculate your Basal Metabolic Rate using the Mifflin-St Jeor equation.
Your BMR
TDEE Calculator
Calculate Total Daily Energy Expenditure based on BMR and activity level.
Your TDEE
| Goal | Calories | Protein | Fat | Carbs |
|---|
Due Date Calculator
Estimate your due date based on your last menstrual period (Naegele's rule).
Pregnancy Estimate
Ideal Weight Calculator
Estimate your ideal body weight using four well-known formulas.
Ideal Weight Estimates
| Formula | Weight (kg) | Weight (lbs) |
|---|
What these six health calculators estimate
The tabs above cover the numbers people most often look up about weight, energy and pregnancy: Body Mass Index, body-fat percentage from tape measurements, basal metabolic rate (BMR), total daily energy expenditure (TDEE) with a simple macronutrient split, an estimated due date, and ideal body weight according to four classic formulas. Every tab except Due Date accepts metric or imperial units, and the calculators that depend on sex have a Male/Female switch because the published formulas use different constants.
These results are estimates for general information only. They are not medical advice, a diagnosis or a treatment plan. The formulas can misjudge athletes, older adults, teenagers, pregnant people and anyone with an unusual build. Talk to a doctor, midwife or registered dietitian before changing your diet, training or medication, and rely on your prenatal care provider for pregnancy dating.
How to use the calculators
- Choose a tab: BMI, Body Fat, BMR, TDEE, Due Date or Ideal Weight.
- Select Metric or Imperial and, where shown, Male or Female. In imperial mode height is entered as feet plus inches (Body Fat uses total inches).
- Enter your measurements. For Body Fat, the usual Navy protocol is to measure the neck just below the larynx, the waist at the navel for men or at the narrowest point for women, and (women only) the hips at the widest point.
- For TDEE, pick the activity level that matches a typical week, not your most active day. For Due Date, enter the first day of your last menstrual period.
- Press Calculate. Results appear under the form with a category or explanation.
Formulas used on this page
| Calculator | Method |
|---|---|
| BMI | weight (kg) ÷ height (m)2, rounded to one decimal. Adult categories: under 18.5 underweight, 18.5–24.9 normal, 25–29.9 overweight, 30 or more obese. |
| Body fat | U.S. Navy circumference equations, with lengths in inches. Men: 86.010×log10(waist − neck) − 70.041×log10(height) + 36.76. Women: 163.205×log10(waist + hip − neck) − 97.684×log10(height) − 78.387. Bands for men: under 6% essential, 6–13.9% athletes, 14–17.9% fitness, 18–24.9% average, 25%+ obese; for women: under 14%, 14–20.9%, 21–24.9%, 25–31.9%, 32%+. |
| BMR | Mifflin–St Jeor: 10 × weight (kg) + 6.25 × height (cm) − 5 × age + 5 for men, or − 161 for women. |
| TDEE | BMR × activity factor: 1.2 sedentary, 1.375 light, 1.55 moderate, 1.725 very active, 1.9 extra active. The table adds rows for −500 and +500 kcal and splits calories 30% protein, 25% fat and 45% carbohydrate (4, 9 and 4 kcal per gram). |
| Due date | Naegele’s rule: first day of last period + 280 days. The current week counts from that date; weeks 0–12 are shown as the first trimester, 13–26 as the second and 27 onward as the third. |
| Ideal weight | Base weight at 5 ft plus a fixed amount per extra inch. Devine: 50 kg (men) / 45.5 kg (women) + 2.3 kg. Robinson: 52 / 49 kg + 1.9 / 1.7 kg. Miller: 56.2 / 53.1 kg + 1.41 / 1.36 kg. Hamwi: 48 / 45.5 kg + 2.7 / 2.2 kg. The range shown is the lowest to highest of the four. |
As a worked example, a 30-year-old man who is 170 cm tall and weighs 70 kg has a BMI of 24.2 and a Mifflin–St Jeor BMR of about 1,618 kcal per day; with the moderately active factor of 1.55 his estimated TDEE is about 2,507 kcal. Imperial inputs are converted with 1 in = 2.54 cm and 1 lb = 0.453592 kg. Every calculation runs in your browser: measurements are not sent to a server and nothing is saved when you leave the page.
Frequently asked questions
Why does BMI call me overweight when I am muscular?
BMI only compares weight with height, so it cannot tell muscle from fat. Muscular people often land in the overweight band. The Body Fat tab or a professional body-composition test gives a better picture in that case.
How precise is the Navy body-fat estimate?
It is an approximation from three or four tape measurements. It can differ from lab methods such as DEXA or underwater weighing by several percentage points, and a centimetre of error in tape placement noticeably moves the result. Measure twice, keep the tape level, and compare readings over time rather than trusting a single number.
My fitness tracker gives a different daily calorie figure. Which is right?
Neither is exact. This page multiplies a population-average BMR by a broad activity factor, while trackers estimate activity from sensors. Use either as a starting point, then adjust based on how your weight actually changes over a few weeks.
How reliable is the due date?
Naegele’s rule assumes a regular 28-day cycle with ovulation around day 14, and only a minority of babies arrive on the estimated day. Early ultrasound dating by a clinician is the usual reference, so treat this date as a rough guide.
Why do the four ideal-weight formulas disagree?
They are simple straight-line rules devised decades ago, largely to estimate drug doses, and each was fitted differently. None accounts for frame size, muscle or age, and they are intended for adults at least 5 ft (152 cm) tall. Treat the range as context, not a target.