Utilities
Calculate BMI in metric or imperial
Calculate body mass index from height and weight, in metric or imperial, with reference ranges and honest caveats.
For the best results: Use total inches for imperial height (5 ft 9 in = 69). The result is a screening number, not a diagnosis, the caveats shown with it matter.
Computed entirely in your browser. Nothing you enter is uploaded, logged, or stored.
What is BMI Calculator?
BMI Calculator is a free online utility that calculates body mass index from height and weight in metric or imperial units, shown against WHO reference ranges with honest caveats. The math runs right in the page, so the numbers you enter stay on your device and are never sent anywhere. There is no account step, no limit on how many times you calculate, and it keeps working offline.
- ✦Runs entirely in your browser. Nothing you enter is ever uploaded
- ✦No account, no sign-up, and no data leaves your device
- ✦Works offline once the page has loaded
See it in action
A routine check: 175 cm and 70 kg.
What you type
Height 175, weight 70, metric
What you get
BMI 22.9, verified in testing, presented against the WHO adult reference ranges with the bands listed rather than a judgmental label.
Tip: BMI is a population screening number, not a diagnosis, and the output frames it that way. Imperial entry works too, height in total inches and weight in pounds.
Use cases
What people use it for
See where a height and weight combination sits against WHO reference ranges in either unit system
Produce the BMI figure an insurance application or gym induction form asks for
Note how the number moves across months without creating an account or being profiled
Who uses BMI Calculator?
Form fillers
obtain the single figure a document demands without enduring a health-site questionnaire first
Fitness beginners
record a baseline number while understanding clearly what it can and cannot say
Nursing students
practice the calculation and the WHO brackets for coursework and placement preparation
How it works
- 1Vary step 1 by tool shape using the existing FORM_TOOL_IDS set in app/(public)/[category]/[tool]/page.tsx. Form tools get "Set the options for what you need." and text tools get "Paste your text into the box." Where a tool's config makes it easy, name its own inputs instead. Steps 2 and 3 stay shared as they are.
- 2Your browser computes the result instantly. Nothing is uploaded anywhere.
- 3Copy the output; the tool keeps working even offline.
Tips for the best results
- Treat the result as a screening statistic, not a verdict about health
- Measure height without shoes and weigh at a consistent time of day for comparable readings
- Watch the trend across months rather than reacting to any single figure
- Adult BMI brackets do not apply to children, who are assessed on age-based percentile charts
- Bring questions about what your figure means to a qualified health professional
FAQ
Frequently asked questions
What does BMI actually measure?
Body mass index is weight in kilograms divided by height in meters squared, a formula devised in the nineteenth century by the statistician Adolphe Quetelet for describing populations, not individuals. It is a rough proxy for body size relative to height and nothing more: it measures neither body fat, nor fitness, nor health, which is why it is best described as a screening statistic.
Why is BMI so widely criticised?
The formula cannot distinguish muscle from fat, so muscular athletes routinely score in ranges suggesting excess weight while carrying very little body fat. It also ignores where weight is carried, and its cutoffs were derived from population studies that do not transfer equally across ages, sexes and ethnic backgrounds. It remains in use because it is cheap and comparable, but a single number was never designed to describe an individual.
What are the WHO reference ranges shown?
The World Health Organization brackets adult BMI as under 18.5, 18.5 to 24.9, 25 to 29.9, and 30 or above. These boundaries were defined for classifying populations in research and public health statistics. What any individual reading means in context is a conversation for a qualified health professional, who will weigh far more than two measurements.
Is the imperial calculation a different formula?
Same formula, adjusted units. The metric version divides kilograms by meters squared; the imperial version divides pounds by inches squared and multiplies by 703, which is simply the unit conversion folded into a single constant. Both routes land on the same figure for the same body, so pick whichever units your scales and measuring tape already speak.
Are my height and weight entries stored anywhere?
Body measurements are sensitive by any definition, and many health sites harvest them for profiling. This page takes the opposite approach: the division happens on your own device, no measurement is transmitted or written to any log, and there is no account to attach a history to. Once loaded it works without a connection, and closing the tab removes every trace.
How do you calculate BMI with pounds and inches?
Multiply weight in pounds by 703, then divide by height in inches squared. Someone weighing 160 pounds at 68 inches works out to 160 times 703 divided by 4624, which is about 24.3. The 703 constant just converts the imperial units into the metric formula's terms.
What is a normal BMI for adults?
The WHO reference range for adults runs from 18.5 to 24.9, though normal here is a statistical label from population research rather than a personal verdict, and researchers continue to debate where cutoffs should sit for different groups. Interpreting your own figure is best done with a health professional.
Is BMI accurate for athletes?
Generally not. Muscle is denser than fat, so rugby players, sprinters and lifters often register in ranges implying excess weight despite low body fat. This blind spot has been documented since the formula's earliest days. Athletes and coaches typically rely on other assessments, chosen with professional guidance.
Are there any usage limits?
None. Everything is generated locally in your browser, so there is no server cost, no metering, and no daily cap, use it as many times as you like, completely free.
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