# Calorie Calculator > Maintenance calories are your BMR times an activity factor: a moderately active 30-year-old man who is 175 cm and 70 kg burns about 2,556 kcal a day (1,649 × 1.55), so eating 2,006 kcal a day loses about 0.5 kg a week. Targets cover losing or gaining 0.25 to 1 kg (0.5 to 2 lb) a week. - Interactive calculator: https://calculatorswithsteps.com/calorie-calculator - Category: Health & Fitness Calculators - Last updated: 2026-11-10 - Publisher: Calculators With Steps (calculatorswithsteps.com) ## How to use the calorie calculator 1. Pick **Metric** (kg, cm) or **US** (lb, ft, in). 2. Enter your sex, age, height and weight. 3. Choose the activity level that matches a typical week. Count your job as well as planned exercise. The result shows your **maintenance calories** (what you burn in a day), your basal metabolic rate and a table of daily calorie targets for losing or gaining weight at different speeds. Any target below the usual safe minimum is flagged. ## How the calorie calculator works First it estimates your basal metabolic rate (BMR), the energy you burn at complete rest, with the **Mifflin-St Jeor equation**: **Men: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age + 5** **Women: BMR = 10 × weight (kg) + 6.25 × height (cm) − 5 × age − 161** Then it multiplies BMR by an activity factor to get your maintenance calories, also called total daily energy expenditure: | Activity level | Factor | What it means | | --- | --- | --- | | Sedentary | 1.2 | Desk job, little or no exercise | | Lightly active | 1.375 | Light exercise or sport 1–3 days a week | | Moderately active | 1.55 | Moderate exercise 3–5 days a week | | Very active | 1.725 | Hard exercise 6–7 days a week | | Extra active | 1.9 | Very hard training or a physical job | Finally it adds or subtracts calories for your goal, using the rule of thumb that 1 kg of body weight holds about 7,700 kcal (3,500 kcal per lb). ## Worked example A 30-year-old man, 175 cm tall and 70 kg, who exercises 3 to 5 days a week: - BMR = 10 × 70 + 6.25 × 175 − 5 × 30 + 5 = **1,648.75 kcal** - Maintenance = 1,648.75 × 1.55 = **2,556 kcal a day** | Goal | Change per week | Calories per day | | --- | --- | --- | | Maintain weight | None | 2,556 | | Mild weight loss | −0.25 kg | 2,281 | | Weight loss | −0.5 kg | 2,006 | | Extreme weight loss | −1 kg | 1,456 (below the 1,500 minimum) | | Mild weight gain | +0.25 kg | 2,831 | | Weight gain | +0.5 kg | 3,106 | In US units the same man at 5 ft 9 in and 155 lb gets 2,563 kcal for maintenance and 2,063 kcal to lose 1 lb a week. The small difference comes from rounding the height and weight. ## How many calories to lose weight A calorie deficit makes your body draw on stored energy. The 7,700 kcal per kg rule says a 550 kcal daily deficit should take off about 0.5 kg a week, and a 500 kcal deficit about 1 lb a week. It is a useful first estimate, but it has limits: - The first week or two often shows a faster drop because you lose stored carbohydrate and water. - As you get lighter you burn less. In the example above, losing 5 kg lowers maintenance from 2,556 to 2,478 kcal, so the same intake gives a smaller deficit. - Your body adapts by moving a little less and becoming more efficient. Research using a dynamic model (Hall et al., 2011) found weight responds slowly: a lasting change of about 100 kJ (24 kcal) a day eventually shifts weight by about 1 kg, with half of that change taking about a year. The NIH Body Weight Planner uses this model if you want a week-by-week forecast. ## Minimum calories and safe rates of loss A loss of 0.5 to 1 kg (1 to 2 lb) a week is the usual guide for adults with weight to lose. Most guidelines also advise against eating below about 1,200 kcal a day for women or 1,500 kcal for men without medical supervision. That floor matters most for smaller, less active people. A 35-year-old woman who is 165 cm, 65 kg and lightly active has maintenance of 1,850 kcal. Losing 0.5 kg a week means 1,300 kcal a day, which is workable, but losing 1 kg a week would mean just 750 kcal. For her, a slower target plus more daily movement is the better route. ## Calories to gain weight To gain weight, eat 275 to 550 kcal a day above maintenance. Combine the surplus with strength training and enough protein, and more of the gain will be muscle rather than fat. The [protein calculator](https://calculatorswithsteps.com/protein-calculator) gives a daily protein target, and the [macro calculator](https://calculatorswithsteps.com/macro-calculator) splits your calories into protein, carbs and fat. ## Tips for using your number - Weigh yourself at the same time each day and compare weekly averages, not single readings. - If your weight hasn't moved after 2 to 3 weeks, lower your intake by 100 to 200 kcal, or raise it if you are losing faster than planned. - Recalculate after every 4 to 5 kg of change. - If you only want your resting burn, use the [BMR calculator](https://calculatorswithsteps.com/bmr-calculator). To compare every activity level side by side, try the [TDEE calculator](https://calculatorswithsteps.com/tdee-calculator). ## Frequently asked questions ### How many calories should I eat a day? It depends on your size, age, sex and activity. A 30-year-old man who is 175 cm tall, weighs 70 kg and is moderately active burns about 2,556 kcal a day. A 35-year-old woman who is 165 cm, 65 kg and lightly active burns about 1,850 kcal. Eating that amount keeps your weight steady. ### How do I calculate my calorie deficit for weight loss? Find your maintenance calories (BMR × activity factor), then subtract the deficit. Losing 0.5 kg a week takes about 550 kcal a day (0.5 × 7,700 ÷ 7), and losing 1 lb a week takes about 500 kcal a day (3,500 ÷ 7). With maintenance of 2,556 kcal, that means eating about 2,006 kcal. ### What is a calorie deficit? A calorie deficit means eating fewer calories than your body burns, so it draws on stored energy, mostly fat. A moderate deficit of 250 to 550 kcal a day is easier to keep up and protects muscle better than a crash diet. ### How many calories should I eat to lose 1 kg a week? Losing 1 kg a week needs a deficit of about 1,100 kcal a day. That is too aggressive for most people. For the 35-year-old woman in our example it would mean eating only 750 kcal a day, far below the usual 1,200 kcal minimum, so a 0.25 to 0.5 kg weekly target is safer. ### How many calories should I eat to gain weight? Add about 275 to 550 kcal a day to your maintenance calories to gain 0.25 to 0.5 kg a week. For a man with maintenance of 2,556 kcal that is 2,831 to 3,106 kcal. Pair the surplus with strength training and enough protein so more of the gain is muscle. ### Is 1,200 calories a day too low? For many women 1,200 kcal is the lowest intake usually advised without medical supervision, and for men the figure is about 1,500 kcal. Going lower makes it hard to get enough protein, vitamins and minerals and speeds up muscle loss. ### How accurate is this calorie calculator? A 2005 systematic review found Mifflin-St Jeor predicted resting metabolism within 10% of measured values in more people than any other common equation. The bigger source of error is the activity level, so treat the result as a starting point and adjust it after 2 to 3 weeks of weighing yourself. ### What is calorie cycling? Calorie cycling means eating more on some days (often training days) and less on others while keeping the same weekly total. Weight change depends on the weekly average, so cycling is a matter of preference rather than a faster way to lose fat. ## Sources - [Mifflin MD et al. – A new predictive equation for resting energy expenditure in healthy individuals (Am J Clin Nutr, 1990)](https://doi.org/10.1093/ajcn/51.2.241) - [Hall KD et al. – Quantification of the effect of energy imbalance on bodyweight (The Lancet, 2011)](https://doi.org/10.1016/S0140-6736(11)60812-X) - [NIH National Institute of Diabetes and Digestive and Kidney Diseases – Body Weight Planner](https://www.niddk.nih.gov/bwp) > Disclaimer: results are estimates for information and education, not medical advice. Confirm important decisions with a qualified professional.