CALORIE CALCULATOR

This calculator does three things. It estimates the energy your body uses at rest, adds how active you are to get your maintenance calories, then adjusts that number for your goal: fat loss, maintenance or building muscle. It also gives you a daily protein target.

Step 1, resting energy. We use the Mifflin-St Jeor equation, built from measurements of 498 healthy adults aged 19 to 78 (Mifflin et al., 1990). A 2005 review comparing four common equations found it was the most reliable. It was the most likely to come within 10% of what people actually burn at rest when measured in a lab, though it can still be well off for some individuals (Frankenfield et al., 2005).

Step 2, maintenance calories. Your resting number is multiplied by your activity level, from 1.2 for a desk job with little exercise up to 1.9 for very hard daily training or a physical job. The result is your TDEE (total daily energy expenditure), which is the same thing as your maintenance calories.

Step 3, your goal and pace. For fat loss you choose a deficit of 10 to 25% below maintenance, with 15% as our default. For building muscle you choose a surplus of 5 to 20% above maintenance, with 10% as our default. For maintenance we leave it as is. The sections below explain what each setting means.

For example, a 30-year-old woman who is 165cm, 65kg and moderately active gets maintenance of about 2,124 calories, a fat loss target of about 1,805 calories at the default 15% deficit and about 111g of protein a day. That is a worked example, not a recommendation for anyone else.

Treat the result as a starting point. Any equation is an estimate, so follow your number for two to three weeks and let your weekly average weight tell you whether to adjust.

A calorie deficit means eating less energy than your body uses, so it makes up the difference from stored energy, including body fat. There is no fat loss without one, whatever the diet is called.

Choose "Lose Fat" and pick your pace on the slider, from 10% to 25% below maintenance. Our default is 15%. In our coaching, that is enough to see steady progress without making training, sleep and everyday life miserable. In a trial of 24 elite athletes who kept lifting weights, the group losing weight more slowly (about 0.7% of body weight a week, or about 0.5kg for a 70kg person, with energy intake cut by about 19%) gained muscle, while the faster group (about 1.4% a week, with intake cut by about 30%) did not (Garthe et al., 2011). These were elite athletes, so treat it as a guide to pace rather than a rule for everyone.

Choosing your fat loss pace

• Gentle (10% deficit). About 10% below maintenance. Slower progress, but the easiest to live with: hunger, energy and training barely change. A good fit if you are already fairly lean, training hard, or want fat loss to feel close to unnoticeable.
• Steady (15% deficit). About 15% below maintenance, our coaching default. Steady, visible progress without making training, sleep and everyday life miserable. The best place for most people to start.
• Faster (20% deficit). About 20% below maintenance. Quicker results, with more hunger and lower energy at times. In a trial of 24 elite athletes who kept lifting, the group that cut energy intake by about 19% still gained muscle while losing weight. Keep protein high and keep lifting.
• Aggressive (25% deficit). About 25% below maintenance. The fastest, and the hardest to sustain: expect more hunger, lower energy and tougher sessions. In the same athlete trial, the group that cut intake by about 30% lost weight faster but did not gain muscle. Best kept to short phases, and not a good fit if you have a history of disordered eating.

What to aim for: in our coaching, about 0.5 to 1kg a week for most people, at the lower end if you are lighter or want to keep as much muscle as possible, judged on the weekly average of morning weigh-ins rather than any single day. Day-to-day readings bounce with water, salt and food, which is why a jump on the scale is rarely fat.

If your weekly average has not moved after two to three weeks, check your tracking first, then we suggest trimming 100 to 200 calories a day. If you are losing much faster than about 1kg a week, eat a little more. Our guide to how many calories to eat to lose fat goes through this step by step.

If you have a medical condition, are pregnant or breastfeeding, or have a history of disordered eating, talk to your GP or an Accredited Practising Dietitian before setting a calorie target.

Choose "Maintain" and your target is simply your maintenance calories. Eat that much on average and your weight should stay roughly where it is.

Maintenance is a useful goal more often than people think. It suits you after a fat loss phase, while you learn your portions, during a busy or stressful stretch, or when you mainly want to get stronger and fitter without chasing the scale. In our coaching, a few weeks at maintenance between phases often makes the next one easier to stick to.

Choose "Build Muscle" and pick your pace on the slider, from 5% to 20% above maintenance. Our default is 10%. Muscle is built by training hard and consistently with weights. The extra food supports that work; it does not replace it.

Smaller surpluses keep fat gain down; bigger ones speed things up. A 2019 review of nutrition for natural bodybuilders suggested a calorie surplus of roughly 10 to 20%, aiming to gain about 0.25 to 0.5% of body weight a week (roughly 0.2 to 0.35kg for a 70kg person) for beginners and intermediates (Iraki et al., 2019). If your weekly average weight is not rising after two to three weeks, we suggest adding a little more food, mostly from carbohydrates to fuel your sessions.

Choosing your muscle gain pace

• Lean (5% surplus). About 5% above maintenance. Slow, careful gains with the least fat. Suits experienced lifters, who build muscle more slowly, or anyone who wants to stay lean while they build.
• Moderate (10% surplus). About 10% above maintenance, the bottom of the 10 to 20% range a 2019 review suggested for natural bodybuilders. A solid starting point for most people who lift consistently.
• Faster (15% surplus). About 15% above maintenance. Faster weight gain, and in our experience more of it ends up as fat. A good step up if your weekly average weight is not rising at the lower settings.
• Maximum (20% surplus). About 20% above maintenance, the top of that review's range. The fastest gains, and the most fat gain alongside them. Best for people who find it genuinely hard to put on weight.

New to lifting? Pair this with our guide on weights or cardio to see how training fits in.

For most people who exercise, the International Society of Sports Nutrition recommends 1.4 to 2.0g of protein per kg of body weight a day (Jäger et al., 2017). As our coaching standard within that range, this calculator uses 1.7g per kg for women and 1.8g per kg for men, for every goal.

Protein helps you hold on to muscle in a deficit and build it in a surplus, and in our experience it makes meals more filling. For the detail, see how much protein to eat to lose fat and how much protein to eat per meal.

• Don't add exercise calories back. Your activity level is already in the number. Fitness trackers are a poor guide anyway: in a study of 60 adults testing seven wrist-worn trackers, even the most accurate one was off by a median of 27% for calorie burn (Shcherbina et al., 2017).
• Count the easy-to-miss calories. Cooking oil, dressings, nut butter and sauces add up quickly, which is often why eating healthy doesn't lead to weight loss.
• Think in weeks, not days. A slightly higher day balanced by a lower one lands in the same place over the week.
• Recalculate as you change. As your weight or activity changes, so does your maintenance. We suggest running the calculator again every 4 to 6kg or when your routine changes.

Hitting a calorie and protein target every day is the hard part. INCHECK FIT builds your meal plan around these exact numbers, with the quantities and shopping list worked out for you.

• How big should my calorie deficit be? For fat loss, this calculator lets you choose a deficit of 10 to 25% below your maintenance calories. Our coaching default is 15%. In our coaching, most people do well losing about 0.5 to 1kg a week, judged on the weekly average of morning weigh-ins. In a trial of 24 elite athletes, the group that lost weight more slowly (about 0.7% of body weight a week, with energy intake cut by about 19%) gained muscle, while the faster group (about 1.4% a week) did not. They were elite athletes, so treat it as a guide to pace rather than a rule.
• How accurate is a calorie calculator? It is a well-informed starting estimate, not a measurement. A 2005 review that compared four common equations found Mifflin-St Jeor, the one this calculator uses, was the most reliable and the most likely to land within 10% of measured resting metabolism, though individuals can still be further off. Follow your number for two to three weeks, then adjust it based on what your weekly average weight does.
• Should I eat back the calories I burn exercising? No. Your activity level is already built into your calorie target, so adding exercise calories on top counts them twice. Fitness trackers also guess calorie burn poorly: in a 2017 study of 60 adults testing seven wrist-worn trackers, even the most accurate one was off by a median of 27% for calorie burn.
• How many calories should I eat to build muscle? Eat a little more than maintenance and train with weights consistently. This calculator lets you choose a surplus of 5 to 20% above maintenance, with 10% as our default. A 2019 review of nutrition for natural bodybuilders suggested a calorie surplus of roughly 10 to 20% and gaining about 0.25 to 0.5% of body weight a week for beginners and intermediates. If your weekly average weight is not rising, we suggest moving the slider up a step.
• How much protein do I need a day? For most people who exercise, the International Society of Sports Nutrition recommends 1.4 to 2.0g of protein per kg of body weight a day. As our coaching standard within that range, we suggest 1.7g per kg for women and 1.8g per kg for men, whether your goal is losing fat, maintaining or building muscle.
• Why am I not losing weight on my calorie target? Check the trend before changing anything, because daily weight swings with water, salt and food in your gut. If your weekly average has not moved in two to three weeks, the usual reason is that intake is higher than it looks: cooking oils, sauces and spreads are easy to underestimate, and that is normal, not a lack of effort. Tighten up the tracking first, then we suggest trimming 100 to 200 calories a day if needed.
• What is the difference between BMR, TDEE and maintenance calories? BMR (basal metabolic rate), or resting energy, is roughly the energy your body uses at rest. TDEE (total daily energy expenditure) is your BMR plus everything you do in a day, from walking to training. Your TDEE is your maintenance calories: eat that much on average and your weight should stay roughly the same.

1. Mifflin MD, St Jeor ST, Hill LA, Scott BJ, Daugherty SA, Koh YO. "A new predictive equation for resting energy expenditure in healthy individuals." American Journal of Clinical Nutrition. 1990;51(2):241-247. PMID: 2305711. DOI: 10.1093/ajcn/51.2.241 [Equation development study, human, n=498 healthy adults aged 19 to 78, resting energy measured by indirect calorimetry. Verified 25 Sep 2026 via Europe PMC; coefficients match the paper.]
2. Frankenfield D, Roth-Yousey L, Compher C. "Comparison of predictive equations for resting metabolic rate in healthy nonobese and obese adults: a systematic review." Journal of the American Dietetic Association. 2005;105(5):775-789. PMID: 15883556. DOI: 10.1016/j.jada.2005.02.005 [Systematic review of four equations in healthy nonobese and obese adults. Abstract verified 13 Oct 2026 via Europe PMC.]
3. Garthe I, Raastad T, Refsnes PE, Koivisto A, Sundgot-Borgen J. "Effect of two different weight-loss rates on body composition and strength and power-related performance in elite athletes." International Journal of Sport Nutrition and Exercise Metabolism. 2011;21(2):97-104. PMID: 21558571. DOI: 10.1123/ijsnem.21.2.97 [Randomised trial, human, n=24 elite athletes doing resistance training. Abstract verified 13 Oct 2026 via Europe PMC.]
4. Iraki J, Fitschen P, Espinar S, Helms E. "Nutrition recommendations for bodybuilders in the off-season: a narrative review." Sports. 2019;7(7):154. PMID: 31247944. DOI: 10.3390/sports7070154 [Narrative review, natural bodybuilders. Abstract verified 13 Oct 2026 via Europe PMC.]
5. Jäger R, Kerksick CM, Campbell BI, et al. "International Society of Sports Nutrition Position Stand: protein and exercise." Journal of the International Society of Sports Nutrition. 2017;14:20. PMID: 28642676. DOI: 10.1186/s12970-017-0177-8 [Position stand. Verified 12 Oct 2026 via Europe PMC: 1.4 to 2.0g per kg body weight a day for most exercising people.]
6. Shcherbina A, Mattsson CM, Waggott D, Salisbury H, Christle JW, Hastie T, Wheeler MT, Ashley EA. "Accuracy in wrist-worn, sensor-based measurements of heart rate and energy expenditure in a diverse cohort." Journal of Personalized Medicine. 2017;7(2):3. PMID: 28538708. DOI: 10.3390/jpm7020003 [Validation study, human, n=60 adults, 7 devices; median calorie-burn error 27% for the most accurate device and 93% for the least. Verified 25 Sep 2026 on the publisher page.]