Question 1

What is a BMI calculator?

Accepted Answer

A BMI calculator is a tool that computes your Body Mass Index — a numerical value derived from your height and weight. The formula is: BMI = weight (kg) ÷ height² (m). It categorises your result as Underweight (<18.5), Normal (18.5–24.9), Overweight (25–29.9), or Obese (≥30). SuperBMI goes further by supporting multiple standards (CDC, NHS, WebMD), family profiles, a live avatar visualizer, and a holistic health score.

Question 2

What is the BMI calculator for females?

Accepted Answer

The BMI calculator formula is the same for females and males: weight (kg) ÷ height² (m). However, women naturally carry more body fat than men at the same BMI. The NHS standard adjusts risk thresholds for South Asian and Chinese women, where the healthy range is 18.5–22.9 instead of the standard 18.5–24.9. SuperBMI's female BMI calculator lets you select gender and ethnicity for a more personalised result.

Question 3

Is the BMI calculator accurate?

Accepted Answer

BMI is a useful screening tool but not a perfect diagnostic measure. It does not distinguish between fat and muscle — a muscular athlete may show an 'overweight' BMI with very low body fat. It also doesn't account for fat distribution (visceral vs. subcutaneous fat), age-related body changes, or gender differences in body composition. For this reason, SuperBMI combines BMI with sleep, hydration, exercise, and mood data to give you a more complete health picture.

Question 4

How to use the BMI calculator?

Accepted Answer

Using SuperBMI is simple: (1) Go to the Calculator page. (2) Select your BMI standard — CDC, NHS, or WebMD. (3) Choose your unit system — metric (kg/cm) or imperial (lbs/in). (4) Enter your gender, age, height, and weight using the input fields or sliders. (5) Your BMI, category, healthy weight range, and health score update instantly. You can also set a target weight and click 'Preview goal body' to see your future silhouette.

Question 5

How accurate is the BMI calculator?

Accepted Answer

BMI calculators are mathematically precise — the formula always produces the same result for a given height and weight. The accuracy limitation is in how well BMI represents true health risk. Studies show BMI correctly classifies obesity risk in roughly 50–70% of cases when compared to direct body fat measurement. SuperBMI improves accuracy by offering the NHS ethnicity-adjusted standard and the WebMD body-frame standard, which provide more personalised thresholds than the generic CDC ranges.

Question 6

How much should I walk according to my BMI?

Accepted Answer

General walking recommendations by BMI category: Normal weight (18.5–24.9) — 30 minutes/day (7,000–8,000 steps) to maintain health. Overweight (25–29.9) — 45–60 minutes/day (10,000 steps) to support gradual weight loss. Obese (≥30) — start with 20–30 minutes and build up to 60+ minutes daily; even 10-minute walks reduce cardiovascular risk. SuperBMI's 30-day '10k Steps Streak' challenge helps you build a daily walking habit with progress tracking.

Question 7

How does the BMI calculator work?

Accepted Answer

The BMI calculator divides your weight by the square of your height. For metric units: BMI = kg ÷ m². For imperial: BMI = (lbs ÷ in²) × 703. SuperBMI performs this calculation client-side in your browser in real time — no server involved. It then compares your result to the thresholds of your chosen standard (CDC, NHS, or WebMD) to determine your category, and feeds the BMI into the holistic health score algorithm alongside your lifestyle inputs.

Question 8

How do I calculate my BMI manually?

Accepted Answer

To calculate BMI manually in metric: divide your weight in kg by your height in metres squared. Example: 75 kg ÷ (1.75 × 1.75) = 75 ÷ 3.0625 = 24.5 BMI (Normal weight). In imperial: multiply weight in pounds by 703, then divide by height in inches squared. Example: 165 lbs × 703 = 115,995 ÷ (69 × 69 = 4,761) = 24.4 BMI. Or simply use SuperBMI's free calculator for instant results.

Question 9

What is a good BMI number?

Accepted Answer

A good (healthy) BMI using the CDC standard is between 18.5 and 24.9 for adults. Below 18.5 is Underweight; 25–29.9 is Overweight; 30 and above is Obese. For South Asian and Chinese adults (NHS standard), the healthy range is 18.5–22.9. For children aged 2–19, a healthy BMI is between the 5th and 85th percentile for their age and sex. The 'ideal' BMI within the healthy range is generally considered to be around 21–23.

Question 10

Can I use the BMI calculator for children?

Accepted Answer

Yes. SuperBMI supports child BMI calculation for ages 2 and above. For children under 20, the CDC standard interprets BMI as a percentile relative to peers of the same age and sex, since healthy BMI ranges change significantly during development. You can create a separate family profile for each child and track their BMI over time alongside lifestyle data.

Question 11

Does SuperBMI store my health data?

Accepted Answer

No. SuperBMI runs entirely in your browser. All data — profiles, weight logs, BMI history, badges, challenge progress — is stored locally in your browser's localStorage. Nothing is ever sent to a server. There are no user accounts, no cloud sync, and no analytics that could identify you. Your health data is completely private and belongs only to you.

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