BMI (WHO): 5 Mistakes to Avoid
Calculates BMI with the international WHO categories. The maths is not complicated, but a handful of errors come up again and again in this and related health & fitness calculations. Here is what to watch for.
Energy needs depend on age, sex, size and activity. Formulas such as Mifflin-St Jeor estimate resting needs, and an activity multiplier turns that into daily needs. Real requirements vary by a few hundred calories, so adjust based on how your weight changes over several weeks.
Research has shown that Asians tend to develop conditions such as type 2 diabetes and heart disease at lower body weights than Europeans. That is why the Health Promotion Board recommends lower BMI cut-offs for Singaporeans, with 23 marking the start of moderate risk.
1. Using international BMI cut-offs for Asians
HPB recommends lower cut-offs because risks rise at lower BMIs in Asian populations.
2. Relying on a single measurement
Weight and heart rate fluctuate daily; trends tell you more.
3. Mixing units
Entering pounds or inches into a metric formula gives nonsense results.
4. Treating estimates as exact
Formulas such as BMR or body fat are population estimates with real margins of error.
5. Measuring inconsistently
Tape measurements change with posture and breathing; measure the same way each time.
The correct method
BMI = kg ÷ m².
For example, with these inputs:
- Weight (kg): 68
- Height (cm): 170
the calculator returns:
- BMI: 23.53
- WHO category: Normal weight
Related calculations
- Running Pace Calculator: Calculates pace for runs like the Standard Chartered Marathon or IPPT 2.4 km.
- Calories Burned Calculator: Estimates calories burned with MET values.
- BMI Calculator (Asian Cut-offs): Singapore's Health Promotion Board uses lower BMI cut-offs for Asians because health risks rise at lower BMIs.
- BMR Calculator: Estimates calories your body burns at rest.
The BMI Calculator (WHO) applies the formula consistently, so it is a quick way to double-check your own working.
Run your own numbers: BMI Calculator (WHO)