A little understanding. Your kind of balance.

Find your daily calorie needs.

Explore estimated daily calories for maintaining weight, losing weight or supporting muscle growth. A useful starting point, based on published research.

For generally healthy adults aged 18 and over. This educational calculator gives estimates, not a diet plan or personalised medical advice.

What would you like to explore?

A few details about you

Why does the equation ask this?

The original research used separate male and female equations. These categories do not capture every body or hormonal situation, including gender-affirming hormone treatment. The result can be less reliable when the original categories do not fit you.

Weight
Height

The times shown are examples of exercise hours per week, not strict cut-offs. Choose the closest overall level, including work, everyday movement and exercise intensity. Exercise is already included in the estimate.

Use a healthcare professional instead if you are pregnant or breastfeeding, have an eating disorder or a history of one, or have a medical condition, medication or prescribed diet that affects your weight or nutrition. Under-18s need a different approach.

Your entries are used in this calculator only. They are not saved to your customer account or sent by the calculator to BALANCE.

How we calculate your estimate

We use the Mifflin–St Jeor equation to estimate resting energy expenditure, then multiply by an approximate activity factor for daily needs. The activity categories are broad assumptions, not an individually validated measurement. The weight-loss scenario is 15% below this estimate; the muscle-growth scenario is 5% above it. These are transparent BALANCE design choices within commonly used approaches, not percentages proven best for everyone.

Female equation: (10 × weight in kg) + (6.25 × height in cm) − (5 × age) − 161.

Male equation: (10 × weight in kg) + (6.25 × height in cm) − (5 × age) + 5.

Activity factors: mostly sitting ×1.2; lightly active ×1.375; moderately active ×1.55; very active ×1.725; exceptionally active ×1.9.

How accurate is it?

A study-based estimate is more useful than applying the same calorie number to everyone, but we do not claim to be more accurate than every other calculator. Mifflin–St Jeor performed well against other resting-metabolism equations in a systematic review; individual errors remained, and that does not establish the accuracy of a full daily calorie estimate. Age, body composition, health and activity estimates can affect results. Measuring resting metabolism is different from estimating it.

Why your needs can change

Energy needs can change as body weight, activity and metabolism change. This is a snapshot based on your current details. It does not implement the NIH Body Weight Planner’s dynamic model and does not calculate a goal-weight date. Compare estimates with your longer-term experience rather than treating a number as a fixed requirement.

The evidence behind the estimate

Three research starting points, with their strengths and limits. These sources do not endorse BALANCE or this calculator.

1. Resting energy · Mifflin–St Jeor

The original equation was developed from measured resting energy expenditure in 498 adults. A later systematic review favoured it over the other commonly used equations it examined, while identifying individual errors and limited representation of some groups.

Read the original study ↗ · Read the systematic review ↗

2. Changing needs · NIH / NIDDK

Research behind the Body Weight Planner models how energy needs and body weight change over time. It supports explaining why a fixed calorie deficit cannot predict a precise long-term weight outcome. Our simpler calculator uses a current-day estimate instead.

Read the NIH / NIDDK research ↗

3. Muscle growth · Helms and colleagues

A small eight-week trial compared maintenance with intended 5% and 15% energy surpluses during resistance training. Faster weight gain mainly increased fat gain; extra muscle benefit was less clear. There were only 17 completers, so this does not establish one ideal surplus for everyone.

Read the muscle-growth study ↗

Related public guidance

NHS information explains energy balance and who should seek individual advice. NICE reserves low-energy diets of 800–1,200 kcal/day for supported services in specified circumstances. We therefore withhold low weight-loss figures here. A higher figure is not automatically suitable for every person.

NHS: calories and weight loss ↗ · NICE: energy intake and support ↗

Sources checked: 14 October 2026. Educational estimates; no diet plans or individual dietary advice.