Tool

Energy & BMI Calculator

Log a day of food for kilojoules, calories and macros; check it against your daily energy need (RDA) and your BMI.

What did you eat today?

FoodAmountkcal
No foods added yet.

Today's totals

0 kcal
0 kcal
0 kJ
Protein0 g · 0%
Carbs0 g · 0%
Fat0 g · 0%

About you

Your daily energy need (RDA)

0
kcal / day · 0 kJ
Eaten today0 kcal
Daily need0 kcal

BMI & healthy weight

0
1518.5253040

How this calculator works — and its limits

Method & assumptions

  • Daily energy need is estimated with the Mifflin-St Jeor equation (a widely used, published formula), multiplied by your selected activity level.
  • Food values are per-100g composition figures typical of standard food-composition tables; brands and preparation methods vary, so logged totals are estimates.
  • All outputs are population-level estimates — individual metabolism can differ by several hundred kcal/day.

BMI is a screening measure, not a diagnosis

  • BMI cannot distinguish muscle from fat — it over-reads for muscular people and can under-read for older adults with low muscle mass.
  • It is not valid in pregnancy, and children need age-adjusted centile charts, not this scale.
  • Health risk can start at lower BMI values for people of South Asian, Chinese, other Asian, Middle Eastern, Black African or African-Caribbean backgrounds (NHS uses 23 rather than 25 as the overweight threshold).
  • Concerned about your weight or energy needs? A GP or registered dietitian can assess properly — this tool can't account for medical conditions or medications.
VitaWhat is an educational reference only. It is not medical advice and is not authoritative. Always consult a qualified healthcare professional before making changes to your diet, supplements or treatment. See how this content is produced in our editorial policy; report an error via the contact page.