Estimate Your Daily Calories and Macros
Use metric or imperial measurements to calculate an educational estimate of daily energy needs and an example split of protein, carbohydrate and fat.
The figures are starting estimates, not personalised targets or medical advice. Your actual needs can differ because equations cannot account for every aspect of health, body composition, medication, training or daily life.
Check whether this tool is suitable for you
This calculator is intended for generally healthy adults aged 18 or over who want to understand how common energy equations work. It cannot diagnose a health concern or prescribe an eating plan.
Do not use this calculator as a dietary target if you:
- are under 18, pregnant or breastfeeding;
- have a diagnosed or suspected eating disorder, are in recovery, or find calorie tracking distressing or compulsive;
- have experienced unintentional weight loss;
- follow a medically prescribed diet or have a condition that affects nutrition, metabolism, growth or fluid balance; or
- have been advised by a healthcare professional not to count calories or macros.
Ask your GP, registered dietitian or another suitably qualified healthcare professional for individual advice. If tracking brings anxiety, guilt, restriction or pressure, stop using the figures and seek support.
Calculate an educational estimate
Choose the option that best reflects an average week. Activity descriptions are only approximations; selecting a higher level can substantially increase the result.
Educational estimate
Selected-goal energy example
— kcal/day
This number is calculated from the information you entered and rounded to the nearest 10 kcal. It is not a precise measurement of what your body needs.
- Estimated resting energy (BMR)— kcal/day
- Estimated maintenance energy (TDEE)— kcal/day
- Selected adjustment—
How the calculation works
The tool separates the calculation into resting energy, an activity estimate, an optional goal example and a clearly disclosed macro split.
Estimate resting energy
The Mifflin–St Jeor equation estimates basal metabolic rate (BMR) from weight, height, age and one of two sex-based constants: 10 × kg + 6.25 × cm − 5 × age + 5 for the male equation, or the same calculation minus 161 for the female equation.
Apply an activity multiplier
BMR is multiplied by the activity level selected to estimate total daily energy expenditure (TDEE). These categories are broad estimates; work, movement, training and recovery vary from one week to another.
Apply the selected example
Maintenance leaves estimated TDEE unchanged. The gradual-loss example shows 10% below it, while the gradual-gain example shows 5% above it. These are illustrative settings rather than clinical or sports-nutrition recommendations.
Convert the example into macros
The displayed split uses 20% protein, 50% carbohydrate and 30% fat. Protein and carbohydrate are calculated at 4 kcal per gram and fat at 9 kcal per gram. Different patterns may also support a balanced diet.
Activity multipliers used
| Calculator choice | Multiplier | Important limitation |
|---|---|---|
| Mostly seated | 1.20 | May still include ordinary day-to-day movement. |
| Light exercise | 1.375 | Training duration and intensity can differ widely. |
| Moderate exercise | 1.55 | Three to five sessions do not automatically produce the same energy use. |
| Hard exercise | 1.725 | Choose this only when the description reflects a typical week. |
| Very hard training or physical work | 1.90 | This high estimate will not suit most people. |
How to interpret the estimate
Expect uncertainty
A formula is not a laboratory measurement. Treat the result as a broad reference point, not a number you must hit exactly.
Think beyond one day
The NHS Eatwell Guide describes balance across a day or week. Appetite, schedules and meals naturally vary.
Notice wellbeing
Energy, concentration, mood, training recovery and your relationship with food matter. Do not ignore symptoms to follow a calculated number.
Seek individual support when needed. A registered dietitian can consider medical history, food access, culture, preferences, symptoms and goals in a way this calculator cannot. Speak to a GP about unexplained weight change, persistent fatigue, dizziness, digestive symptoms or other health concerns.
Helpful next reads
Frequently asked questions
Is this a personalised calorie target?
No. It is an estimate from a population equation and a broad activity multiplier. It does not assess your health, body composition, symptoms, medication, training programme or nutritional requirements.
Why does the calculator ask for sex?
The Mifflin–St Jeor equation was published with separate male and female constants. This tool describes the field as “sex used by the equation” and does not claim that two options reflect everybody’s identity or physiology.
Are the macro figures recommendations?
No. They illustrate one 20% protein, 50% carbohydrate and 30% fat split. This convention will not be suitable for everyone, and different balanced patterns are possible.
Can I use this calculator during pregnancy or breastfeeding?
No. Energy and nutrient needs change during pregnancy and breastfeeding, and this general adult equation is not designed to account for them. Ask a midwife, GP or registered dietitian for suitable advice.
Does Lifestyle Hub Today store my information?
No. The calculation runs in your browser. This tool does not send or save the age, sex, height, weight, activity or goal details you enter.
Method and trusted guidance
- Mifflin MD et al. (1990): A new predictive equation for resting energy expenditure in healthy individuals
- NHS: The Eatwell Guide
- NHS: Adult BMI calculator limitations and exclusions
- NICE NG246: Overweight and obesity management
Editorial note: Lifestyle Hub Today provides general educational information. No medical reviewer, dietitian review or individual assessment is claimed. Sources and calculator assumptions were checked on 2 September 2026.
About Lifestyle Hub Today
We create practical lifestyle guides and free tools designed to make everyday planning feel clearer and more manageable. Read more about Lifestyle Hub Today or explore our free resources.