This calorie calculator estimates a daily maintenance level from a Mifflin–St Jeor constant, age, weight, height, and an activity multiplier. Choose men (+5) or women (−161). The shared part of the equation is 10 times weight in kilograms, plus 6.25 times height in centimeters, minus 5 times age in years. The constant you chose is added last. That basal figure is then multiplied by the activity number you type.
The two constants differ by 166 kcal before activity is applied. On the sample adult, age 30, 75 kg, and 175 cm, the men's basal estimate is 1,698.75 calories and the women's is 1,532.75. At a 1.55 multiplier the headlines are 2,633 calories/day and 2,376 calories/day. The result is an estimate of maintenance calories, not a prescribed intake, and it is not a basal metabolic measurement from a lab. Body mass index, on the separate BMI page, does not use this equation at all.
A measured run is a different number from this multiplier. A 5 kilometre finish of 25:00 is 5:00 per kilometre, 8:02.8 per mile, and 12 km/h on the 5K pace calculator. That pace describes one session. It does not replace the 1.55 you type here, and this page will not turn the pace into a calorie burn. Use the two results side by side: maintenance is the daily estimate, and the pace page is the speed of a distance you already timed.
How to use this calculator
- Choose Men (+5) or Women (−161). The sample starts on the men's constant.
- Enter age in years, weight in kilograms, and height in centimeters.
- Enter an activity multiplier as a plain number. A common moderate factor is 1.55. The field is not a menu.
- Press Calculate. The headline is basal calories times that multiplier, rounded to the nearest calorie. The first detail line is the basal estimate before activity, and the next line names the constant you chose.
How the Mifflin–St Jeor estimate is built
Mifflin–St Jeor estimates resting energy expenditure. Weight is in kilograms, height is in centimeters, and age is in years. The men's equation is 10×weight + 6.25×height − 5×age + 5. The women's equation replaces the final +5 with −161. This form applies the constant you select. It does not infer the constant from a name or from a body measurement. The two constants differ by 166 kcal before activity is applied, and that gap scales with the multiplier. At 1.55 the gap is 166 × 1.55 = 257.3 calories, which is the distance between the two sample headlines after rounding.
Resting expenditure is not the maintenance target most people want. Maintenance is closer to resting expenditure times a factor that stands in for movement. This calculator multiplies by whatever number you enter. It does not look up your job, steps, or workouts. If you type 1, you get the resting estimate alone, rounded to a whole calorie. Switching the constant and leaving the multiplier at 1 is the clean way to compare the two basal figures.
The headline is that product rounded to the nearest calorie. The first detail line prints the basal estimate before rounding to a whole calorie, with up to two decimal places. For the sample man that line is 1,698.75 calories. For the sample woman it is 1,532.75 calories. The second line names the equation, either men (+5) or women (−161), so a saved result still says which constant produced it.
Formula
BMR (men) = 10×kg + 6.25×cm − 5×age + 5 BMR (women) = 10×kg + 6.25×cm − 5×age − 161 Choose one constant. The form does not average them. Maintenance estimate = BMR × activity multiplier The headline rounds that product to the nearest calorie. The basal line shows BMR before that rounding, up to two decimal places.
The activity multipliers people usually type are conventions attached to the equation later, not part of the original Mifflin–St Jeor paper. A common set is 1.2 for little movement, 1.375 for light activity, 1.55 for moderate activity, 1.725 for a very active week, and 1.9 for heavy training or a physical job. They are rough. Two people who both type 1.55 will not spend the same energy.
Rounding uses the same rule as the on-screen number. A product of 2,038.5 displays as 2,039 calories/day. The page quotes the displayed calorie count, not a truncated one.
Worked calorie examples
Age 30, 75 kg, 175 cm, multiplier 1.55
Choose men (+5). Basal estimate = 10×75 + 6.25×175 − 5×30 + 5 = 750 + 1,093.75 − 150 + 5 = 1,698.75. The basal line reads 1,698.75 calories. Times 1.55 is 2,633.0625. The calculator shows 2,633 calories/day, and the equation line says men (+5).
Switch the constant to women (−161) and leave age, weight, height, and 1.55 in place. The basal estimate is 1,698.75 − 166 = 1,532.75, and 1,532.75 × 1.55 = 2,375.7625, which rounds to 2,376. The calculator shows 2,376 calories/day, the basal line reads 1,532.75 calories, and the equation line says women (−161). The button applies the constant. You do not subtract 166 by hand.
The same person at the other common multipliers
Holding age, weight, and height at 30, 75 kg, and 175 cm, and keeping the men's constant, the basal estimate stays 1,698.75. Times 1.2 is 2,038.5, shown as 2,039 calories/day. Times 1.375 is 2,335.78125, shown as 2,336. Times 1.725 is 2,930.34375, shown as 2,930. Times 1.9 is 3,227.625, shown as 3,228.
The same body with the women's constant has a basal estimate of 1,532.75. The headlines are 1,839 at a 1.2 multiplier, 2,108 at 1.375, 2,376 at 1.55, 2,644 at 1.725, and 2,912 at 1.9. The span from 2,039 to 3,228 on the men's side, or from 1,839 to 2,912 on the women's side, is the activity guess. If you are unsure which factor fits, calculate two neighbors and treat the gap as uncertainty.
Two other adult examples
Age 45, 90 kg, 182 cm, multiplier 1.375, men's constant. Basal estimate = 10×90 + 6.25×182 − 5×45 + 5 = 900 + 1,137.5 − 225 + 5 = 1,817.5. The basal line reads 1,817.5 calories. Times 1.375 is 2,499.0625. The calculator shows 2,499 calories/day. The same inputs with the women's constant use 1,651.5 as the basal estimate and show 2,271 calories/day.
Age 25, 60 kg, 165 cm, multiplier 1.725, women's constant. Basal estimate = 10×60 + 6.25×165 − 5×25 − 161 = 600 + 1,031.25 − 125 − 161 = 1,345.25. Times 1.725 is 2,320.55625. The calculator shows 2,321 calories/day, and the basal line reads 1,345.25 calories. Choosing the men's constant on this body instead would add 166 to the basal estimate before the multiplier. The equation line is what tells you which one the headline used.
Activity multipliers for one sample adult, both constants
| Multiplier you type | Common name for that factor | Men (+5) | Women (−161) |
|---|---|---|---|
| 1.2 | Sedentary, little exercise | 2,039 | 1,839 |
| 1.375 | Light activity | 2,336 | 2,108 |
| 1.55 | Moderate activity | 2,633 | 2,376 |
| 1.725 | Very active | 2,930 | 2,644 |
| 1.9 | Extra active or physical work | 3,228 | 2,912 |
Limits of a maintenance estimate
Predictive equations miss individual metabolism. Illness, medications, pregnancy, lactation, and significant muscle or fat differences move true needs away from the formula. A lab measurement of resting metabolism will not match 10×kg + 6.25×cm − 5×age + 5, or the same equation with −161, exactly. The constant is a population offset, not a measurement of the person in front of you.
The activity factor is the largest judgment on the page, and it is entirely yours. Overestimating activity overestimates maintenance. The calculator cannot see step counts or training logs.
Maintenance is not a weight-loss or weight-gain prescription. Eating less than maintenance tends to reduce weight and eating more tends to increase it, but the size and speed of that change are not calculated here. Medical diets, eating disorders, and clinical nutrition need a professional, not a single multiplied equation.
Do not feed a race time into the activity field. The 5K pace calculator keeps the arithmetic in minutes and kilometres: 25:00 for 5 kilometres is exactly 5:00 per kilometre, and the same pace projects a half marathon of 1:45:29.3 and a marathon of 3:30:58.5 using 21.0975 km and 42.195 km. None of those clocks is a calorie total. Holding the sample man at 1.55 still displays 2,633 calories/day whether or not you also run that 5K. The pace page will not accept a weight, and this page will not accept a finish time.
Frequently asked questions
Does this calorie calculator use the women's Mifflin–St Jeor equation?
Yes, when you choose Women (−161). The men's choice uses plus 5. For the sample 30-year-old at 75 kg, 175 cm, and a 1.55 multiplier, the men's path displays 2,633 calories/day and a basal line of 1,698.75. The women's path displays 2,376 calories/day and a basal line of 1,532.75. The equation line under the headline names the constant that was used.
What activity multiplier should I type?
The form does not choose one. Common values people pair with this equation are 1.2, 1.375, 1.55, 1.725, and 1.9, from little movement up to heavy daily activity. They are rough labels. If you are between two of them, run both and treat the difference as uncertainty.
Is the result a weight-loss target?
No. It is an estimate of maintenance calories: the basal equation times your multiplier. The page does not subtract a deficit, add a surplus, or predict how quickly weight would change.
Why is the result a whole number of calories?
The product of the basal estimate and the multiplier is rounded to the nearest calorie for the headline. The sample basal estimate 1,698.75 times 1.2 is 2,038.5, and the calculator shows 2,039 calories/day.
What is the difference between the basal estimate and the headline?
The basal estimate is the Mifflin–St Jeor resting figure, printed on its own line before activity is applied. The headline multiplies it by the activity number you typed and rounds to the nearest calorie. Type 1 if you want the resting figure alone in the headline. For the sample man, the basal line stays 1,698.75 calories at every multiplier.
Can a 25:00 5K replace the activity multiplier?
No. The multiplier is a judgment about the whole day. The 5K pace calculator converts 25:00 for 5 kilometres into 5:00 per kilometre, 8:02.8 per mile, and 12 km/h, then projects that pace onto a 10K, a half marathon, and a marathon. Those clocks are not calories. The sample man at 1.55 remains 2,633 calories/day on this page.
Related ClearCalc pages
- Adult BMI calculator Weight in kilograms and height in centimeters, as a screening category. It does not estimate calories.
- 5K pace calculator Minutes per kilometre and per mile from a finish time. A 25:00 5K is 5:00 per kilometre. It does not estimate calories.
- Percentage calculator Useful if you want a percent difference between two calorie figures you already have. It does not run Mifflin–St Jeor.