How to Calculate a Calorie Deficit: Formula, Examples, and Table

By the nucoach editorial team · Updated September 17, 2026 · approx. 12 min read

What is a calorie deficit?

A calorie deficit means that you take in less energy over the day than your body burns. It gets the difference from its own reserves, ideally from body fat. This is the only physiological condition under which weight loss works, regardless of eating style, diet trend, or training method.

The equation has 2 sides. On the expenditure side is your total daily energy expenditure (TDEE), meaning everything your body burns in a day: basic functions like breathing, heartbeat, and cell renewal, plus every movement from climbing stairs to working out, and the energy that digestion itself costs. On the intake side is everything you eat and drink. When intake is below expenditure, the deficit arises.

Why calculating makes sense in the first place: most people overestimate their expenditure and underestimate their intake, both by several hundred calories. If you lose weight by feel, you often end up in a deficit that either doesn’t exist at all or is far too big. A one-time calculation gives you a realistic starting point that you then fine-tune based on actual progress. The basics, meaning what pace is healthy and why strength training remains indispensable in a deficit, are explained in the weight loss guide.

Step 1: How do you calculate your basal metabolic rate?

Your basal metabolic rate (BMR) is the energy your body needs at complete rest to keep your organs, brain, and body temperature running. For most people, it makes up 60 to 70 percent of total expenditure and depends on weight, height, age, and sex.

The most accurate common formula is the Mifflin-St Jeor formula. In practice, it has largely replaced the older Harris-Benedict formula because, for today’s body compositions, it comes closer to measured values:

Here is what the calculation looks like with real numbers:

An important caveat: the formula gives an average value for people with your stats. If you have a lot of muscle mass, your real value is higher; if you have little, it’s lower. The difference is usually around plus or minus 10 percent, and that is exactly why the calculation is a starting point, not a law of nature. How much muscle mass really contributes to expenditure, and which myths circulate about it, is covered in the guide Boost Your Metabolism.

Which formula is the right one?

There are 3 common formulas for BMR, and for most people Mifflin-St Jeor is the best choice because it doesn’t require a body fat measurement and comes closest to measured values. The other two have their place in special cases.

The Harris-Benedict formula dates from 1919, with a revision in 1984. It is still the default in many online calculators, but for most people it overestimates BMR by 5 to 10 percent, because it is based on a population with a different body composition. If you calculate with it, you often start with too many calories and wonder why nothing is happening.

The Katch-McArdle formula calculates with lean body mass instead of total weight: BMR = 370 plus 21.6 x lean body mass in kg. It is the most accurate of the 3 but requires that you know your body fat percentage, and reasonably reliably at that. Bathroom scales with body fat measurement fluctuate by several percentage points depending on time of day and hydration, which wipes out the formula’s advantage again. It makes sense for people with a very high or very low amount of muscle mass, for whom Mifflin-St Jeor is clearly off, and when body fat has been measured professionally.

In practice, that means: calculate with Mifflin-St Jeor, check the result against the scale after 3 weeks, and correct. This feedback is more accurate than any formula, because it measures your body instead of an average.

Step 2: How do you calculate your total expenditure?

Your total daily energy expenditure (TDEE) is calculated by multiplying your BMR by an activity factor, the so-called PAL value (physical activity level). It reflects how much you actually move in daily life and in training, and ranges between 1.2 and 1.9.

The most common mistake at this point: almost everyone picks a factor one level too high. Two workouts a week with a desk job put you at factor 1.375, not 1.55, because you spend the remaining 165 hours of the week sitting, lying, or walking. When in doubt, pick the lower level. If you then lose weight faster than planned, you can add calories at any time; the other way around is more frustrating.

For the woman in the example above with a factor of 1.375: 1,429 x 1.375 gives about 1,965 kcal of TDEE. For the man with a factor of 1.55: 1,780 x 1.55 gives about 2,759 kcal.

Step 3: How big should your calorie deficit be?

For most goals, a deficit of 300 to 500 kcal per day is the best starting point. It is big enough for visible progress and small enough to preserve muscle, energy, and mood.

Why more isn’t better: from a deficit of around 750 kcal, the risk rises significantly that the body breaks down muscle along with fat, that cravings blow up your discipline, and that training performance collapses. Nobody keeps up a deficit that feels like constant struggle for 3 months, and that is exactly how long it takes for results to become visible.

A second rule is just as important: your daily calories should not stay below your BMR long term. The deficit is subtracted from TDEE, never from BMR. For the woman in the example, that means: 1,965 TDEE minus 400 deficit gives about 1,565 kcal a day, and that is comfortably above her BMR of 1,429 kcal. If the calculation puts you below your BMR, choose a smaller deficit and increase your activity instead.

2 worked examples step by step

Both examples use the same sequence: BMR, activity factor, TDEE, deficit, daily calories. Just plug in your own values.

Here is how to use the table for yourself: enter your stats in the first row, calculate your BMR with the formula from step 1, choose the activity factor one level too low rather than too high, and set the deficit according to the table from step 3. The check row is mandatory: if your daily calories are below your BMR, the deficit is too big.

Both figures are starting values. After 2 to 3 weeks, the scale shows whether the estimate fits: if your weight drops at the expected pace, everything stays as it is. If nothing happens, the real deficit is smaller than calculated, usually because intake has been underestimated. If it goes much faster and you feel sluggish, the deficit is too big and you add 100 to 200 kcal.

How fast will you lose weight with the deficit?

The rule of thumb: One kilogram of body fat corresponds to about 7,000 kcal. With a 500 kcal deficit per day, that adds up to 3,500 kcal per week, or about half a kilo of fat. With 300 kcal, it is about 300 grams per week.

The scale, however, tells a different story than the math. In the first week, your weight often drops by 1 to 2 kg, mostly water, because with the calorie reduction, the carbohydrate stores and the water bound to them shrink, too. After that, the curve flattens and fluctuates: stress, intense training, salty food, and, for women, the menstrual cycle lead to water retention of 1 to 2 kg that masks fat loss for days.

That is why daily values don’t count, but the trend over 2 to 3 weeks does. It’s best to weigh yourself in the morning after getting up, always under the same conditions, and calculate the weekly average. Circumference measurements at the waist and hips also help, because fat loss with simultaneous muscle gain shows up there earlier than on the scale. Realistic expectation for 3 months with a moderate deficit: 4 to 6 kg of fat, visible in the mirror and in how your clothes fit.

For Anna from example 1, the timeline looks like this: week 1 minus 1.5 kg, most of it water. Weeks 2 to 4 about 0.4 kg each, with individual days when the scale seems stuck or even goes up. After 12 weeks, about 5 kg less, one clothing size smaller, and a TDEE that should be recalculated. If you know this pattern in advance, you’ll get through weeks 2 to 4, the stretch where most attempts fail.

How do you track calories properly?

At the start, it’s worth doing a phase of 2 to 3 weeks of precise tracking; after that, rough rules are enough for most people. The tracking phase isn’t a permanent solution but a calibration: it shows you where your calories really come from.

Here is how to do it cleanly: weigh everything you eat and drink with a kitchen scale and enter it in a tracking app, including oil, sauces, drinks, and the leftovers from your kid’s plate. Estimating by eye is typically off by 20 to 30 percent, almost always on the low side. You scan packaged foods by barcode, for unpackaged foods you use the app’s database values, and at restaurants you estimate on the generous side.

What matters is the balance over the week, not the single day. A restaurant evening 800 kcal over target is not a problem if the other 6 days fit, because your body doesn’t calculate in 24-hour windows. If you look at the weekly total on Sunday evening and divide by 7, you have a more honest number than someone who either celebrates or despairs every evening.

After the 3 weeks, you know your standard meals and their values, and from then on the deficit works without weighing your food, too: fixed portion sizes, protein with every meal, the plate method, and no liquid calories. If you notice that your weight is stalling, simply track again for a week and find the gap.

Why doesn’t the math add up in everyday life?

Almost always for one of 4 reasons: underestimated intake, overestimated expenditure, falling expenditure in a deficit, or water retention. All 4 can be recognized and fixed.

What is almost never the reason, by contrast, is a broken metabolism. The differences in BMR between people of the same size and composition are smaller than most people think. With persistent exhaustion, sensitivity to cold, or unintended weight change, however, your thyroid should be checked by a doctor before you turn the dials on the deficit.

How do you adjust your deficit over time?

A deficit isn’t a fixed number for 6 months. Three adjustments are part of it: recalculating as you lose weight, building in planned breaks, and tapering the deficit off toward the end.

Recalculate: with every kilo lost, your BMR drops slightly, because less body mass has to be supplied. After 4 to 5 kg of weight loss, you therefore recalculate everything once. For Anna from example 1 at 65 kg, that means: BMR about 1,379 kcal, TDEE about 1,896 kcal, daily calories with a 400 kcal deficit about 1,496 kcal. If you keep the old number, after a few weeks you have a smaller deficit than you think and wonder about the plateau.

Build in breaks: after 8 to 12 weeks in a deficit, a diet break of 1 to 2 weeks is worthwhile, in which you eat at your current TDEE, meaning you neither lose nor gain weight. That relieves your hormone balance and your mind, normalizes appetite, and makes the next phase easier. If you stay in a deficit for 6 months straight, you tend to fight yourself more than the extra kilos from month 3 onward.

Tapering off: once you reach your goal, you raise calories step by step by 100 to 150 kcal per week until your weight stays stable. If you jump straight from the deficit back to your old diet, you usually have your old weight back within a few months. Strength training and protein remain central in this phase, too, because preserved muscle keeps expenditure stable.

How do you stick with the deficit day to day?

The number is one thing, sticking with it is another. Four levers make a deficit workable in everyday life: protein, volume, strength training, and cutting liquid calories.

Protein first: 1.6 to 2.2 g per kilogram of body weight per day, spread across 3 to 4 meals. Protein keeps you full the longest, protects muscle in a deficit, and takes the most energy to digest. For Anna from example 1, that is 110 to 150 g per day, so a clear protein source with every main meal. Which foods deliver it efficiently and how protein works for muscle building is covered in the guide Muscle Building Nutrition.

Volume: vegetables, salad, legumes, and water-rich foods fill the stomach for few calories. The plate method is the simplest rule: half vegetables, a quarter protein source, a quarter side. If you eat like this, you rarely get the cravings that blow deficits apart.

Strength training: 2 to 3 full-body sessions per week are, in a deficit, the signal to the body to keep muscle and burn fat instead. Without this stimulus, every kilo of weight lost also costs muscle, and expenditure drops permanently as a result. The starter plan is in the guide Strength Training for Beginners.

Liquid calories: soft drinks, juices, milky coffee drinks, and alcohol deliver energy without satiety. Many people find 300 to 500 kcal a day here without changing anything about their food. That is often the entire deficit, without daily life feeling any different. More practical strategies, sorted by impact, are in the guide Weight Loss Tips.

When should you not plan the deficit on your own?

The calculation in this guide is aimed at healthy adults. In some situations, the planning belongs in the hands of a doctor or other professional.

These include a body mass index below 18.5 or above 35, diabetes, thyroid, kidney, or heart conditions, pregnancy and breastfeeding, taking medication that affects metabolism or appetite, as well as teenagers and people over 65, whose needs are calculated differently. And most of all: if food is tied to strong pressure, a need for control, or anxiety for you, counting calories is the wrong path. Then a doctor or nutrition therapy is the right place to turn, and statutory health insurance covers services for this.

For everyone else: calculate once properly, start moderately, evaluate after 3 weeks, and adjust. And if earlier attempts failed on follow-through, a nutrition coach is the most efficient shortcut, because a coach does more than calculate: they guide you along the way. What exactly a coach does and how to recognize a reputable one is explained in the guide to the nutrition coach.

Frequently asked questions about calorie deficits

This guide is for general information and does not replace medical or nutrition therapy advice. The formulas provide estimates for healthy adults. If you have pre-existing conditions, are severely underweight or overweight, are pregnant, or if the topic of food weighs heavily on you, talk to your doctor before changing your diet. You can find, compare, and book verified coaches in the nucoach app, for Berlin and Hamburg.