Calculate your BMI from height and weight in kg/cm or lbs/ft. See your BMI category, healthy weight range, and the BMI chart for men, women, and teens.
A one-page summary of your BMI result — your number, the WHO category, your healthy weight range, and how far you are from BMI 24.9 / 18.5. Useful to keep with a fitness log, share with a coach, or take to a GP appointment. Note: BMI is a screening signal, not a diagnosis. It doesn’t account for muscle mass, frame size, age, or pregnancy, so a clinician should interpret it in context.
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Your weight on the scale doesn't tell you the full story. Two people who both weigh 180 pounds can have completely different health pictures depending on their height, muscle mass, age, and body composition. That's why the ideal body weight calculator and BMI tool are so widely used — they put your weight in context of your height and give you a number that means something. Whether you're trying to understand your current BMI, figure out a healthy target weight, or simply answer "is 165 pounds too much for a 5'5 woman?" — this guide covers it all with real numbers, practical examples, and clear explanations built for everyday people in the USA, UK, and Europe.
BMI stands for Body Mass Index. It's a number derived from your height and weight that gives a quick indication of whether your body weight falls within a healthy range. It was developed in the 1830s by Belgian mathematician Adolphe Quetelet and has been adopted by the WHO, CDC, and NHS as a standard screening tool — not a diagnostic one, but a useful first step.
The formulas are straightforward. In metric units: BMI = weight (kg) ÷ height (m)². In imperial units used in the US: BMI = 703 × weight (lbs) ÷ height (inches)². For UK users who measure in stone, multiply your stone value by 14 to get total pounds, then use the imperial formula. Our BMI Calculator above handles all unit conversions automatically.
A quick example: a woman who is 5'4" (162.6 cm) and weighs 140 pounds (63.5 kg) has a BMI of: 703 × 140 ÷ (64)² = 703 × 140 ÷ 4,096 = 24.0 — right in the healthy range.
The ideal body weight formula is slightly different from BMI. While BMI tells you whether your current weight is in a healthy range, the ideal body weight calculation tells you the specific weight range that is optimal for your height. There are several formulas in use — the most widely referenced is the Devine Formula:
For example, for a man who is 5'10" (10 inches above 5 feet): Ideal weight = 50 + 2.3 × 10 = 73 kg (about 161 lbs). For a woman who is 5'6" (6 inches above 5 feet): Ideal weight = 45.5 + 2.3 × 6 = 59.3 kg (about 131 lbs).
These are reference points, not rigid targets. Use our BMI Calculator alongside the Body Fat Calculator for a more complete picture of your body composition.
One of the most searched questions online is "what is a healthy weight for my height?" Here's a practical reference table covering the most common heights for both men and women, based on the standard BMI healthy range of 18.5–24.9:
These ranges are based on BMI 18.5–24.9 and are the same thresholds used by the CDC, NHS, and WHO. For personalised targets, use our BMI Calculator with your exact measurements.
At 5'5" (65 inches), a BMI calculation gives: 703 × 165 ÷ (65)² = 703 × 165 ÷ 4,225 = 27.5. That falls in the overweight range (25.0–29.9). It's above the healthy BMI threshold but not in the obesity range. Whether it's a concern health-wise depends on factors BMI can't measure — muscle mass, fitness level, age, and waist circumference. Many people at this BMI are perfectly healthy.
For a woman at 5'4" (64 inches), the healthy BMI range of 18.5–24.9 translates to approximately 108–145 pounds (49–66 kg). Below 108 lbs would be underweight; above 145 lbs moves into the overweight category. The midpoint — around 127 lbs — is often cited as the statistical ideal for this height.
For a man at 5'9" (69 inches), the healthy BMI range translates to roughly 125–169 pounds (57–77 kg). A BMI of 22–23 — approximately 148–155 lbs — sits in the middle of the healthy zone and is a commonly recommended target for men of this height.
At 6'0" (72 inches), the healthy range is approximately 140–184 pounds (64–84 kg). Men at this height who are athletic may weigh toward the top of this range due to muscle mass without any health concern. Use our Body Fat Calculator alongside BMI if you're muscular or athletic.
Not all obesity is the same, and the medical community uses a tiered classification to reflect different levels of health risk. Here's the full obesity classification breakdown used by the WHO, CDC, and NHS:
Morbidly obese BMI starts at 40 and represents the highest-risk category. At this level, conditions like type 2 diabetes, heart disease, sleep apnea, and joint deterioration become significantly more likely. If you or someone you know falls into Class III obesity, speaking with a doctor about structured weight management options is strongly advisable — not for cosmetic reasons, but for genuine health protection.
In the UK, the NHS uses slightly adjusted thresholds for people of South Asian, Chinese, Black African, and Middle Eastern backgrounds — the overweight threshold is BMI 23+ and obesity begins at BMI 27.5+ for these groups, reflecting different body composition risks at lower BMI values.
This is one of the most important nuances about BMI. BMI vs body fat are two very different measurements, and confusing them can lead to wrong conclusions.
BMI only uses height and weight — it has no idea whether that weight is muscle, fat, bone, or water. A professional rugby player at 6'2" and 230 lbs might have a BMI of 29.5 (technically "overweight") while carrying only 12% body fat and being in peak physical condition. Conversely, a sedentary person at the same height and weight with 30% body fat would have very different health risks.
Healthy body fat percentage ranges (as guidelines, not absolutes):
For a more complete picture than BMI alone can provide, use our Body Fat Calculator alongside this tool. If you want to track weight loss progress, our Weight Loss Calculator can help you set realistic targets.
A reverse BMI calculator flips the calculation: instead of entering your current weight to find your BMI, you enter your height and a target BMI to find the weight you'd need to reach. This is incredibly useful for setting concrete, measurable weight goals.
The formula reversed: Target weight (lbs) = Target BMI × height (inches)² ÷ 703
Example: A woman at 5'6" (66 inches) wants to reach a BMI of 22 (middle of the healthy range). Target weight = 22 × (66)² ÷ 703 = 22 × 4,356 ÷ 703 = 136.2 lbs (61.8 kg). That's her concrete target. Now she can use our Weight Loss Calculator to plan a realistic timeline to get there.
BMI works differently for children and teenagers aged 2–20. Because children's body composition changes significantly as they grow, a single set of BMI thresholds (like those used for adults) doesn't apply. Instead, BMI percentiles are used — comparing a child's BMI to other children of the same age and sex.
The pediatric BMI calculator (also called child BMI calculator or kids BMI calculator) uses age- and sex-specific growth charts from the CDC. Here's how the percentile ranges translate:
In the UK, the NHS uses a similar system with the UK 1990 growth reference charts (UK90). A child's BMI reading should always be interpreted by a healthcare professional in context of their growth trajectory, not just a single snapshot.
The US Army uses BMI as part of its physical fitness screening. The Army BMI calculator applies gender- and age-adjusted maximum weight limits based on height. If a soldier's BMI exceeds the Army's threshold (typically around 27.5), they may be required to pass a body fat assessment using tape measurements as an alternative. The Army's preferred method is the circumference-based body fat test, but BMI screening is the first filter.
Maximum BMI standards vary slightly by age for Army screening, but as a general guide, a BMI over 27–28 will typically trigger the secondary tape test. Use our BMI Calculator above to check where you stand before any military assessment.
The standard BMI thresholds (18.5–24.9 healthy range) apply to adult women of all ages. However, body composition naturally shifts with age — women tend to gain body fat percentage in their 40s and 50s even if weight stays stable, due to hormonal changes. For this reason, waist circumference (less than 35 inches is the general guideline for women) is often considered alongside BMI as a supplementary health indicator.
Men and women share the same BMI thresholds, but men typically carry more muscle mass, which can cause BMI to overestimate fatness in muscular individuals. Men with broad frames or significant athletic build should use BMI vs body fat percentage comparison rather than relying on BMI alone. A waist circumference below 40 inches is the typical guideline for men as an additional cardiovascular risk indicator.
For adults over 65, many researchers suggest that a slightly higher BMI — around 23–27 — may be protective rather than harmful. This is because some extra body weight in older adults can serve as a reserve during illness or recovery. The NHS and many US geriatric health guidelines now acknowledge this nuance. Blanket application of the 18.5–24.9 range to seniors is increasingly seen as too rigid.
The universally accepted healthy BMI range for adults is 18.5 to 24.9. Below 18.5 is underweight; 25.0–29.9 is overweight; 30 and above is classified as obesity. These thresholds are used by the CDC, WHO, and NHS. Note that for some ethnic groups, the NHS uses adjusted thresholds — overweight begins at BMI 23 for people of South Asian, Chinese, Black African, and Middle Eastern backgrounds.
For a woman at 5'4", the healthy weight range based on BMI 18.5–24.9 is approximately 108–145 pounds (49–66 kg). The Devine Formula for ideal body weight gives approximately 108 lbs as a lower reference point for this height. Most healthcare professionals would consider anywhere in the 110–140 lb range healthy for a 5'4" woman, depending on build and muscle mass.
BMI is a useful screening tool for women but has known limitations. It doesn't distinguish between muscle and fat, which means it can underestimate body fat in sedentary women who have low muscle mass but high fat percentage — sometimes called "normal weight obesity." For a more accurate picture, combining BMI with waist circumference (under 35 inches for women) and body fat percentage gives a much more complete health assessment.
Morbid obesity (now more commonly called severe obesity or Class III obesity) begins at a BMI of 40 or above. Some classifications also include BMI 35–39.9 with significant obesity-related health conditions as qualifying for the same treatment pathway. At BMI 40+, surgical options like bariatric procedures are often considered alongside lifestyle interventions.
For children aged 2–20, BMI is interpreted using age- and sex-specific growth charts rather than fixed thresholds. A child's BMI is compared to other children of the same age and sex, expressed as a BMI percentile. Below the 5th percentile is underweight; between 5th and 85th is healthy; 85th to 95th is overweight; at or above 95th percentile is obesity. Always have a paediatrician interpret a child's BMI in the context of their overall growth pattern.
BMI is calculated purely from height and weight — it has no direct measurement of fat. Body fat percentage measures the actual proportion of your weight that is fat tissue. A muscular person can have a high BMI (overweight by the scale) with a low, healthy body fat percentage. Conversely, someone with a "normal" BMI can still have an unhealthy level of body fat. For the most accurate health assessment, use both measurements together.
The standard BMI range of 18.5–24.9 technically applies to all adults, but emerging research suggests that men over 50 may face lower health risks at a slightly higher BMI of 23–27. Some additional body weight in older men can be protective during illness and supports bone density. However, this doesn't mean weight gain is healthy — it means the lower boundary of concern may be slightly relaxed for this group. Waist circumference (under 40 inches for men) is often a more useful indicator than BMI for men over 50.
Yes — this is sometimes called "metabolically unhealthy normal weight" or "skinny fat." A person can fall within the 18.5–24.9 BMI range while having high visceral fat (fat around the organs), poor blood sugar control, high cholesterol, or low muscle mass. This is why BMI is described as a screening tool, not a diagnosis. If your BMI is healthy but you have other risk factors, speak with your doctor about a more thorough metabolic assessment.
The reverse BMI calculator is used to find out what weight you'd need to reach a specific BMI target. For example, if you're 5'8" and want to reach a BMI of 22, it calculates the exact weight that corresponds to that BMI for your height. This gives you a concrete, measurable goal rather than a vague aim to "lose weight." Use it alongside our Weight Loss Calculator to build a realistic plan.
The BMI formula and thresholds are identical for men and women — there's no gender-adjusted calculation in the standard BMI system. However, because men and women have different natural body fat distributions and muscle mass averages, a given BMI value may carry different health implications depending on sex. This is one reason BMI is often considered alongside waist circumference and body fat percentage rather than in isolation.
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Disclaimer: This BMI calculator and all related content are for informational purposes only and do not constitute medical advice. BMI is a screening tool, not a diagnostic instrument. Always consult a qualified healthcare professional for personalised health and weight guidance.
BMI is calculated the same way for men and women: weight (kg) ÷ height (m)². Example: 70 kg ÷ (1.75 m)² = 22.9. WHO categories apply to adults of both sexes: under 18.5 is underweight, 18.5–24.9 is healthy, 25–29.9 is overweight, 30+ is obese. However, BMI is a crude measure — it doesn't distinguish muscle from fat, so athletes often show as "overweight" with very low body fat.
For most adults, the healthy BMI range is 18.5–24.9. On a 5'10" adult, that is 129–174 lbs (58.5–79 kg). Falling outside this range correlates with elevated health risks but isn't diagnostic on its own. Body composition tools like body fat percentage and waist-to-height ratio give clearer health signals than BMI alone.
The WHO has published modified BMI thresholds for South Asian and East Asian populations due to elevated diabetes and cardiovascular risk at lower BMIs. The overweight threshold drops to 23 (from 25) and obese to 27.5 (from 30). UK NHS guidance specifically recommends using these lower thresholds for patients of South Asian descent. Our BMI calculator includes this adjustment.
Body fat percentage is a more accurate health marker than BMI for most people. Healthy ranges: men 10–20%, women 18–28%. A lean athlete might have a BMI of 27 (classified overweight) with only 12% body fat (excellent health). For anyone who exercises regularly, pair the BMI calculator with the body fat calculator for a realistic picture.
Children and teens use age- and sex-specific BMI percentiles, not adult thresholds. A 12-year-old boy in the 70th percentile is healthy; the 95th percentile is classified obese. The CDC and UK NHS both publish growth charts — our BMI tool returns the raw BMI, and parents should compare against age/sex percentile charts for accurate interpretation.
BMI = weight (kg) ÷ height (m)². Or in imperial: 703 × weight (lbs) ÷ height (inches)².
For most adults, 18.5–24.9. Asian adults: 18.5–22.9 under WHO-modified thresholds used by NHS.
No — muscle weighs more than fat, so athletes often show as "overweight" while being lean. Use body fat percentage for them.
BMI 30+ is obese (WHO), or 27.5+ under WHO modified thresholds for Asian adults.
The formula is identical. Women typically have slightly higher body fat at the same BMI, but the category thresholds apply equally to both.