yCalculator

Calorie Calculator

Last updated: April 2026

Unit system

Sex

yrs
kg
cm

Activity level

Calorie results

Maintain weight

2,565

calories/day

Weight loss

2,052

calories/day

Weight gain

2,950

calories/day

Breakdown

BMR1,655 calories/day
TDEE2,565 calories/day
Activity levelModerate (1.55x)

Weight loss

Moderate calorie deficit for sustainable fat loss.

Maintenance

Estimated calories to maintain current weight.

Weight gain

Moderate calorie surplus for weight gain.

Related calculators:

  • BMR Calculator
  • TDEE Calculator
  • Macro Calculator
  • Calories Burned Calculator

How many calories do you need?

Daily calorie needs start with BMR, the calories your body burns at rest, then add an activity multiplier to estimate TDEE.

Calories for weight loss

Weight loss usually requires a calorie deficit. This calculator uses 80% of TDEE as a moderate target.

Calories for weight gain

Weight gain usually requires a calorie surplus. This calculator uses 115% of TDEE as a moderate target.

About this calculator

The Calorie Calculator estimates daily calorie needs for maintaining, losing, or gaining weight. It combines personal details with activity level and goal assumptions to create a practical starting point. Use it for meal planning, nutrition targets, weight management, or comparing how different activity levels change daily intake.

Calorie target methodology

The calculator estimates maintenance calories from BMR and activity, then applies a surplus or deficit depending on the goal.

  • maintenance calories = BMR x activity factor
  • weight loss target = maintenance calories - chosen deficit
  • weight gain target = maintenance calories + chosen surplus

How to use the calorie estimate

  1. Enter age, sex, height, and weight.
  2. Choose an activity level that reflects your normal week.
  3. Select a goal such as maintain, lose, or gain.
  4. Use the result as an initial calorie target.
  5. Adjust after two to four weeks based on scale trend and measurements.

Worked examples

Maintenance

Input: Estimated TDEE 2,200 kcal/day

Result: Maintenance target around 2,200 kcal/day

Weight loss

Input: TDEE 2,200, deficit 500

Calculation: 2,200 - 500

Result: Target around 1,700 kcal/day

Weight gain

Input: TDEE 2,200, surplus 250

Calculation: 2,200 + 250

Result: Target around 2,450 kcal/day

What a calorie calculator estimates

A calorie calculator estimates daily energy needs from body size, age, sex, and activity level. It is most useful for setting a starting target for weight maintenance, fat loss, or weight gain. The result is not a fixed biological truth; it is an estimate that should be adjusted using real progress over time.

Calories matter because body weight changes when energy intake and energy expenditure are out of balance over time. However, food quality, protein, fibre, sleep, training, stress, and medical factors all influence how easy a calorie target is to follow.

Maintenance, deficit, and surplus

The calculator usually starts by estimating maintenance calories. From there, a target can be adjusted depending on the goal.

Maintenance calories
The estimated intake that keeps body weight broadly stable over time.
Calorie deficit
Eating below maintenance can lead to weight loss if sustained. A moderate deficit is usually easier to maintain than an aggressive one.
Calorie surplus
Eating above maintenance can support weight gain or muscle gain when paired with appropriate training.

Using the result in real life

Treat the first result as a starting target for two to four weeks. Track body weight trends, energy, hunger, training performance, and adherence. If progress is too fast, too slow, or uncomfortable, adjust the target rather than assuming the first estimate was perfect.

Calorie calculator components

A good calorie target is built from several assumptions. The calculator combines your resting energy needs, activity level, and goal to produce a starting number.

Maintenance calories
The estimated intake that keeps weight broadly stable. This is the baseline for weight loss or weight gain targets.
Goal adjustment
A deficit is subtracted for weight loss and a surplus is added for weight gain. The size of the adjustment affects speed, hunger, performance, and adherence.
Protein and food quality
Calories set the energy target, but protein, fibre, micronutrients, and meal structure affect fullness, training recovery, and health.
Tracking period
Daily weight fluctuates from water, salt, carbohydrate intake, menstrual cycle, and digestion. Weekly averages are usually more useful than single weigh-ins.

Weight loss and weight gain targets

A moderate calorie deficit is usually more sustainable than an aggressive one. Faster weight loss can increase hunger, fatigue, and the risk of muscle loss if protein and resistance training are poor. For weight gain, a small surplus can support muscle gain while limiting unnecessary fat gain.

The calculator should not be used to chase extreme targets. If you have a medical condition, are pregnant, are under 18, have a history of eating disorders, or are already very lean, get qualified support before changing intake substantially.

Why calorie estimates differ between calculators

Different calculators may use different BMR equations, activity multipliers, and goal assumptions. A difference of a few hundred calories is common. The most useful calculator is the one you treat as a starting point and then adjust based on actual progress.

Equations used for calorie estimates

Most calorie calculators estimate BMR first, then multiply it by an activity factor. The equation choice affects the starting point. Mifflin-St Jeor is widely used for general adult estimates, Harris-Benedict is an older common equation, and Katch-McArdle may be useful when body fat percentage is known.

EquationWhat it estimatesMain limitation
Mifflin-St JeorBMR from age, sex, height, and weightDoes not directly use body composition
Revised Harris-BenedictBMR from age, sex, height, and weightOlder equation; may differ from modern estimates
Katch-McArdleResting needs from lean body massRequires a reliable body fat percentage

Calories, kilojoules, and food energy

Food labels in the UK commonly show both kilocalories, written as kcal, and kilojoules, written as kJ. In everyday language, one food Calorie means one kilocalorie. The conversion is useful when comparing labels, apps, and nutrition plans.

UnitEquivalent
1 kcal4.184 kJ
100 kcal418.4 kJ
1 kJ0.239 kcal

Energy from macronutrients

Calories come mainly from carbohydrate, protein, fat, fibre, and alcohol. Two foods with the same calories can affect fullness, digestion, and nutrition very differently, so calorie targets should be paired with food quality.

ComponentApproximate kcal per gramNotes
Fat9Energy-dense; important for hormones and absorption of some vitamins
Protein4Supports muscle repair and tends to be filling
Carbohydrate4Main fuel source for many activities
Fibre2Supports digestion and fullness; value varies by type
Alcohol7Adds energy with limited nutritional value

Calorie counting as a method

Calorie counting can work because it makes food intake measurable. It can also improve awareness of portion sizes, snacks, drinks, oils, sauces, and restaurant meals. But it is not the only method, and it can be stressful or unsuitable for some people.

A practical approach is to track consistently for a short period, compare the target with real body-weight trends, then adjust. Daily scale changes can be noisy, so weekly averages are usually more useful than single weigh-ins.

Zigzag calorie cycling

Some people prefer different calorie targets on different days while keeping the same weekly average. For example, a person targeting 14,000 kcal per week could eat 2,000 kcal every day, or use higher days and lower days that still total 14,000 kcal. This can make social meals or training days easier to manage.

Calorie cycling is not magic; the weekly average still matters. It is mainly a flexibility tool. People with medical conditions, pregnancy, eating disorder history, or very low body weight should not use aggressive calorie cycling without professional support.

Common mistakes and edge cases

  • Treating the estimate as a guaranteed result.
  • Choosing an activity level that is too high.
  • Forgetting liquid calories, snacks, and weekend meals.
  • Changing calories too aggressively.
  • Ignoring protein, fibre, and overall diet quality.

Limitations

This calculator provides an estimate only and is not a medical diagnosis.

  • It does not replace advice from a qualified clinician or dietitian.
  • Pregnancy, eating disorders, illness, and medication can require specialist guidance.

Frequently asked questions

How accurate is a calorie calculator?

It gives a starting estimate. Real-world progress should guide adjustments.

How fast should I lose weight?

A moderate deficit is usually easier to sustain than an aggressive one.

Do I need to track calories forever?

No. Many people use tracking temporarily to learn portion sizes and habits.

Why am I not losing weight at the target?

Possible reasons include tracking error, lower activity, water retention, or an overestimated TDEE.

Should macros matter too?

Calories drive weight change, but protein, fats, carbohydrates, fibre, and micronutrients affect health and adherence.

Related calculators

  • TDEE Calculator
  • BMR Calculator
  • Macro Calculator
  • Protein Calculator

What does this mean?

This calculator is designed to help you understand the likely number before you make a decision or start an application.

Your result should be checked against official UK guidance, especially if your circumstances include dependants, exemptions, prior leave, or a complex immigration history.

Treat the figure as a planning tool rather than legal advice. Where the answer affects an application deadline or major payment, speak to an authorised adviser.

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