Estimate your basal metabolic rate and daily calorie needs with Mifflin-St Jeor or Harris-Benedict, right in your browser.
Basal metabolic rate is the energy your body spends doing nothing at all: breathing, pumping blood, keeping your temperature stable and renewing tissue. For most people it accounts for 60% to 75% of everything they burn in a day, which is why it is the starting point of any calorie estimate. This tool uses the Mifflin-St Jeor equation, published in 1990 in the American Journal of Clinical Nutrition, which validation studies have repeatedly found to be the most accurate of the general-purpose predictive equations. The classic alternative, Harris-Benedict from 1919 in the revision by Roza and Shizgal (1984), is available in the selector and its result is always shown side by side, because seeing the two numbers disagree is the clearest way to understand that both are estimates.
Your daily total comes from multiplying the basal rate by an activity factor: 1.2 for a sedentary routine, 1.375 for light exercise one to three days a week, 1.55 for moderate exercise three to five days, 1.725 for intense training six or seven days, and 1.9 for a physical job or two sessions a day. From that total the calculator derives two reference targets — a 20% deficit for losing weight and a 10% surplus for gaining — proportions chosen because they are gradual enough to be sustainable. As a rough guide, a kilogram of body fat holds around 7,700 kcal, so a deficit of 500 kcal a day corresponds to roughly half a kilo a week.
Treat every number here as a starting point to be adjusted with real-world results, not as a measurement. Even the best predictive equation misses individual measured metabolism by around 10% in either direction, and more than that for people at the extremes of weight, because it knows nothing about your body composition, thyroid function, medication or genetics. Equations based on lean mass, such as Katch-McArdle, are more precise but require a body fat measurement. The estimates are also not designed for children and adolescents, pregnant or breastfeeding women, competitive athletes or people with metabolic conditions. Weigh yourself over a few weeks, watch the trend, and adjust — and if you are planning an aggressive deficit, do it with a doctor or a registered dietitian. Everything is calculated in your browser and nothing is sent to any server.
Mifflin-St Jeor (weight in kg, height in cm, age in years): men BMR = 10 × weight + 6.25 × height − 5 × age + 5; women BMR = 10 × weight + 6.25 × height − 5 × age − 161. Harris-Benedict revised by Roza and Shizgal (1984): men BMR = 88.362 + 13.397 × weight + 4.799 × height − 5.677 × age; women BMR = 447.593 + 9.247 × weight + 3.098 × height − 4.330 × age. Daily total = BMR × activity factor (1.2 · 1.375 · 1.55 · 1.725 · 1.9). Targets: lose = total × 0.8; gain = total × 1.1.
Mifflin-St Jeor is the current recommendation: it was built on a more modern sample and validation studies find it closer to measured metabolism. Harris-Benedict is kept here for comparison and because many older tables and textbooks still use it.
Yes. BMR is what you would burn lying still all day; the daily total adds movement, work, training and digestion. Eating at your BMR while living a normal life means a much larger deficit than you think.
The 20% deficit shown here is a conservative reference, roughly 400 to 600 kcal a day for most adults. Larger cuts speed things up in the short term but tend to cost muscle mass and are hard to sustain, and going far below this should be supervised by a professional.
Because the number is an estimate with a margin of error of about 10%, and because water retention, sodium, sleep and the menstrual cycle move the scale for days at a time. Track the trend over three to four weeks and adjust the total up or down from there.
No. Age, weight, height and every result stay on your device — the calculation is plain JavaScript and nothing is uploaded or stored.
Vai.la turns any URL into a short link with click statistics, QR Code and your own biolink.
Vai.la is not responsible for how the tools are used or for decisions made based on their results.