Calculate your daily calorie target and timeline to reach your goal weight
This calculator provides estimates based on the Mifflin-St Jeor equation. Actual results vary. Consult a healthcare professional before starting any weight loss programme. Do not go below 1,200 kcal/day (women) or 1,500 kcal/day (men) without medical supervision.
Weight loss is fundamentally about creating a sustained calorie deficit: consuming fewer calories than your body burns each day. While this principle is simple, the execution requires knowing your personal calorie needs, which depend on your age, sex, height, weight, and activity level. This calculator uses the Mifflin-St Jeor equation, widely considered the most accurate formula for estimating Basal Metabolic Rate (BMR) in healthy adults, to calculate your daily energy expenditure and determine a calorie target that will help you lose weight at your chosen rate. The NHS recommends a safe and sustainable rate of weight loss of 0.5 to 1 kg per week for most adults. Losing weight faster than this can lead to muscle loss, nutritional deficiencies, fatigue, and a phenomenon called metabolic adaptation, where your body reduces its energy expenditure in response to prolonged severe restriction. This calculator enforces minimum calorie floors of 1,200 kcal per day for women and 1,500 kcal per day for men, in line with NHS guidance. Going below these levels without medical supervision increases the risk of nutrient deficiency and other health complications. The calculator also generates a weight projection chart showing your estimated weekly progress toward your goal. Keep in mind that real weight loss is rarely linear. Daily fluctuations due to water retention, hormonal cycles, and meal timing are completely normal. The projection is a guide to help set realistic expectations, not a guarantee.
To plan your weight loss: 1. Enter your current weight in kilograms. Weigh yourself first thing in the morning on an empty stomach for the most consistent reading. 2. Enter your height in centimetres and your age in years. These values are used in the Mifflin-St Jeor BMR equation. 3. Select your biological sex. This affects the BMR calculation because men and women have different average metabolic rates due to differences in muscle mass and body composition. 4. Choose your typical activity level. Be honest. Most people with desk jobs who exercise 1-2 times per week are "lightly active" at most. Overestimating activity level is one of the most common reasons weight loss stalls. 5. Enter your target weight. The NHS suggests that even losing 5-10% of your body weight can produce significant health benefits. 6. Select your weekly loss rate. A rate of 0.5 kg per week requires a daily deficit of about 550 kcal and is sustainable for most people. A rate of 1.0 kg per week requires a larger deficit of about 1,100 kcal per day and demands more discipline. 7. Review the results. The calculator shows your BMR, TDEE, daily calorie target, the number of weeks to reach your goal, and an estimated target date. The chart shows your projected weight over time.
This calculator uses the Mifflin-St Jeor equation, published in 1990 and validated as one of the most accurate predictive equations for BMR in healthy adults. For men: BMR = (10 x weight in kg) + (6.25 x height in cm) - (5 x age in years) + 5 For women: BMR = (10 x weight in kg) + (6.25 x height in cm) - (5 x age in years) - 161 Your Total Daily Energy Expenditure (TDEE) is calculated by multiplying BMR by an activity factor: sedentary = 1.2, lightly active = 1.375, moderately active = 1.55, very active = 1.725, extremely active = 1.9. The daily calorie deficit needed is calculated as: daily deficit = (weekly loss rate in kg x 7,700) / 7. The figure 7,700 represents the approximate number of calories stored in 1 kg of body fat. Your daily calorie target is: daily calories = TDEE - daily deficit. For example, a 30-year-old man weighing 80 kg, 175 cm tall, sedentary, wanting to lose 0.5 kg per week: BMR = 800 + 1093.75 - 150 + 5 = 1748.75 kcal. TDEE = 1748.75 x 1.2 = 2098.5 kcal. Daily deficit = (0.5 x 7700) / 7 = 550 kcal. Daily target = 2099 - 550 = 1549 kcal. The weeks to reach the goal is simply: weeks = (current weight - target weight) / weekly loss rate.
If your calculated calorie target falls below 1,200 kcal per day (women) or 1,500 kcal per day (men), this calculator enforces a floor at those levels. To create a larger deficit safely, consider increasing your physical activity rather than further reducing food intake. If you have a BMI over 30, or any medical conditions including diabetes, heart disease, or a history of disordered eating, consult your GP or a registered dietitian before starting a calorie-restricted diet. Weight loss medications and very low calorie diets (VLCDs) should only be undertaken under medical supervision.