Rates & sources
Population-average body composition metrics. Always consult a qualified clinician before making health decisions.
Source: NHS — Health A-Z — figures refreshed at the start of each tax year.
When to use this calculator
- Before setting a new health goal or checking whether a plan is realistic.
- When you want to compare different assumptions without tracking them manually.
- When you need a quick baseline before discussing the result with a professional.
- When you are starting a new fitness or diet programme and want an objective starting-point measurement.
- When you want to recheck your numbers after several weeks of change to see whether the metrics are moving in the right direction.
A realistic South Africa planning example
Use these sample inputs as a quick scenario test, then change one variable at a time to compare outcomes.
Height (cm)
178 cm
After entering these figures, review healthy weight range and midpoint together rather than in isolation — each metric tells a different part of the story. Then rerun the tool with one input adjusted to see which variable has the biggest effect on all three outputs before you settle on a plan.
How to read your results
Healthy Weight Range
This output shows a planning range based on standard BMI thresholds, not a prescriptive personal target, so apply it with context and common sense. Use it as a reference point alongside advice from a healthcare professional rather than as a standalone goal.
Midpoint
Use this metric to compare scenarios side by side and understand how changes in the key inputs drive the final outcome. If the figure surprises you, isolate one variable at a time and rerun the calculation to identify which assumption is responsible.
Method & assumptionsAuthoritative sources
Ideal weight calculators use established formulas — most commonly Hamwi, Devine, or Robinson — to produce an estimated healthy weight range based on height and sex. These formulas were originally developed for clinical applications such as medication dosing, not as personal fitness targets. They do not account for body composition, frame size, age, ethnicity, or fitness level, all of which meaningfully influence what a healthy weight looks like for any given individual. The resulting figure is best interpreted as a broad reference point rather than a goal in itself. Rather than focusing solely on reaching a specific weight, consider also tracking waist circumference and consulting a GP or registered dietitian for personalised guidance.
Common mistakes
- !Using optimistic assumptions without testing a more cautious scenario as well.
- !Comparing outputs from different tools without checking that the inputs match.
- !Treating the result as a final figure rather than a broad planning indicator.
- !Entering estimated rather than accurately measured height or weight, which can shift BMI or healthy-weight results meaningfully.
- !Interpreting a single metric in isolation instead of reading it alongside the other outputs the tool provides.
What to do next
- Rerun the calculator in six to eight weeks with updated measurements to track progress objectively.
- Use the related health calculators to build a fuller picture before discussing any changes with a professional.
- Open one of the linked guides if you want more context on what the metrics mean and how they relate to each other.
- If a result falls outside the normal range, book a GP appointment to discuss it rather than acting on the figure alone.
- Note the date alongside your results so you have a clear before-and-after record when you recheck later.
Frequently asked
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End-of-article next steps
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