BMR & Calorie Calculator

What question does this calculator answer?

Most calorie calculators stop at one number: how many calories you burn in a day. This one goes a step further. It first estimates your basal metabolic rate (BMR) and your total daily energy expenditure (TDEE), which is the amount of food energy that roughly keeps your weight steady. Then, if you give it a goal weight and a deadline, it works backwards to the daily intake that would get you there and checks whether that plan is something a normal body can sustain. If you only want the background on BMR and TDEE, theBMR and TDEE Calculator covers it in more depth. If you are not sure whether your goal weight is sensible in the first place, check it against the BMI Calculator or theIdeal Weight Calculator before you plan the calories.

Important: everything on this page is a general-purpose estimate for adults. It is not medical advice, not a diet prescription, and not a substitute for a doctor or registered dietitian.

How the calculation works, step by step

1. BMR uses the Mifflin-St Jeor equation. For men: 10 x weight (kg) + 6.25 x height (cm) - 5 x age + 5. For women the final term is -161 instead of +5.
2. TDEE is BMR multiplied by an activity factor between 1.2 (sedentary) and 1.9 (very heavy training or a physical job). It is your estimated maintenance level.
3. Total energy change is the absolute difference between current and goal weight multiplied by 7,700 kcal, the commonly used planning figure for one kilogram of body fat.
4. Daily adjustment is that total divided by the number of days (weeks x 7).
5. Daily target is TDEE minus the adjustment when losing weight, or TDEE plus the adjustment when gaining.

The tool then runs two sanity checks. If a loss target falls below your BMR, or if the weekly loss exceeds about 1 percent of your body weight, it shows a warning. Neither line is a medical rule. They are rough screening thresholds meant to catch plans that are very likely to be unpleasant or hard to keep up.

How much does each activity level add?

The activity factor is the part of the calculation people misjudge most often. The table shows what each factor does to a sample BMR of 1,500 kcal, computed when the page is built. The "extra" column is the energy that factor assumes you burn on top of BMR through movement, work, and exercise.

The jump from the sedentary row to the moderate row is bigger than most people expect, which is why picking a level one notch too high is the classic error. If you train three times a week but spend the other hours at a desk, "light" is usually the more honest choice than "moderate".

How fast is too fast? Deficit by weekly pace

Because the plan is built on 7,700 kcal per kilogram, doubling the pace doubles the daily deficit. The table is generated from that assumption.

Many general weight-management guides describe a gradual pace of roughly half a kilogram to one kilogram per week as typical. The catch is that a fixed number of kilograms means something very different for different bodies. A daily deficit of 1,100 kcal can be a bit over a third of the maintenance calories of a large person and nearly half for a small one. That is why this tool also looks at the pace as a percentage of body weight instead of only in kilograms.

Worked examples, double-checked

Example A: 34-year-old woman, 163 cm, 68 kg, light exercise, goal 62 kg

BMR = 10 x 68 + 6.25 x 163 - 5 x 34 - 161 = 1,368 kcal. TDEE = BMR x 1.375 = 1,881 kcal. Losing 6 kg is 6 x 7,700 = 46,200 kcal.

• 12 weeks: a deficit of 550 kcal a day gives an intake of 1,331 kcal, which is below her BMR of 1,368 kcal. The tool flags this, and the sensible response is to give the plan more time.
• 16 weeks: a deficit of 413 kcal gives an intake of 1,468 kcal. That is above BMR, and the pace of 0.375 kg a week is under 1 percent of body weight, so no warning appears.

Example B: 40-year-old man, 175 cm, 85 kg, light exercise, goal 78 kg

BMR is 1,749 kcal and TDEE is 2,405 kcal. Seven kilograms over 14 weeks (98 days) is 53,900 kcal in total, or a 550 kcal daily deficit, so the target intake is about 1,855 kcal. The pace is 0.5 kg a week, around 0.6 percent of his weight, comfortably inside the check.

Example C: gaining, 28-year-old man, 180 cm, 82 kg, moderate exercise, goal 84 kg in 10 weeks

BMR is 1,810 kcal and TDEE is 2,806 kcal. Two kilograms is 15,400 kcal, spread over 70 days is 220 kcal a day on top of maintenance, giving a target of about 3,026 kcal. A surplus of this size is modest. Whether the added weight ends up as muscle or fat depends on training and protein intake, which this arithmetic cannot see.

Why 7,700 kcal per kilogram is only an approximation

The "one kilogram of fat equals 7,700 kcal" rule is a planning shortcut, and real bodies do not follow it exactly. As you lose weight your BMR and the energy cost of moving around both fall, so the same food intake produces a smaller deficit over time. The weight that leaves the scale is also not pure fat: water and some lean tissue are part of it, particularly in the first weeks. This is why progress often looks faster at the start and then seems to stall. Treat the output as a starting point, weigh yourself under similar conditions a few times a week, and review the plan every two to three weeks rather than once.

Common mistakes and misunderstandings

• Choosing an activity level that is too generous. Overestimating inflates your maintenance figure, so the "deficit" is smaller than you think and the scale barely moves. Estimate exercise calories separately with the Exercise Calorie Calculator.
• Eating back every calorie a device says you burned. Wearables and gym machines tend to overstate energy burned, so refunding the full amount erases the deficit.
• Setting a deadline that is too short. Cutting hard for an event a few weeks away can push intake under BMR, which usually backfires through fatigue, lost muscle, and rebound eating.
• Looking only at calories. Two diets with the same calories can differ in how filling they are and how much lean mass they preserve. See the Protein Intake Calculator for the protein side.
• Judging progress by the scale alone. Waist measurement and body fat can improve while weight sits still. The Body Fat Calculator helps you track that from tape measurements.

When not to rely on this calculator

• If you are pregnant or breastfeeding, or under 18 and still growing, because energy needs are different.
• If you have diabetes, a thyroid condition, kidney disease, or any condition treated with medication or a prescribed diet.
• If you have a history of disordered eating or notice that counting numbers is taking over your thinking.
• If your BMI is already in the underweight range and you are considering losing more.

The Mifflin-St Jeor equation can also drift further from reality for people with unusually high or low body fat or a lot of muscle. No formula can promise your actual metabolic rate.

Turning the result into a routine

1. Follow the target as a two-week average rather than a daily pass-or-fail test, and log your weight two or three times a week under the same conditions, such as the morning before eating.
2. If the two-week average moves more slowly than planned, adjust intake by about 100 to 150 kcal rather than making a big change.
3. If the target comes out below your BMR, lengthen the timeline or raise daily movement, for example more walking, instead of cutting food further.
4. When you reach your goal, recalculate TDEE with your new weight and move back toward maintenance gradually.

A note on accuracy and privacy

The figures here are reference estimates based on widely used equations. Real needs vary with muscle mass, genetics, hormones, sleep, and health status. If you have a medical condition or need supervised weight management, speak with a doctor or registered dietitian. Everything you type is calculated in your browser and is not sent to a server.

Frequently Asked Questions