How many calories do you actually need?
Your body burns energy all day, even at complete rest, to run your brain, heart, lungs, liver and temperature control. That resting burn is your basal metabolic rate (BMR). Everything you do on top of rest, from walking to the bus to training for a race, adds to it. The total is often called maintenance calories or TDEE: eat roughly that amount and, on average, your weight stays about the same; eat steadily less and weight tends to fall; eat steadily more and it tends to rise.
No formula can know your exact burn. Bodies of the same size differ, activity is hard to judge honestly, and food labels themselves are approximate. The value of a calculator like this one is a sensible starting point that you then adjust using real feedback: if your weight trend over three or four weeks is not moving the way the target predicts, nudge the target by 100 to 200 kcal and check again. This page is for information only and is not medical advice.
The Mifflin-St Jeor formula
Published in 1990, the Mifflin-St Jeor equation predicts resting energy use more accurately for modern adults than older formulas. Maintenance calories are then BMR × an activity multiplier, from 1.2 for a desk-bound day with no exercise to 1.9 for very hard training or a heavy physical job.
Choosing your activity level and goal
Most people overestimate activity. Steps, standing and housework count, but a single gym session does not turn a mostly seated week into an athlete week, so pick the level that matches your average week, not your best day. For goals, a deficit of about 500 kcal a day corresponds, in simple energy terms, to roughly half a kilogram a week, while 250 kcal a day is a gentler pace that many people find easier to sustain. Targets on this page are never shown below 1,500 kcal a day for men or 1,200 kcal a day for women; very low intakes belong under professional supervision, not a web page.
Worked example
A 30-year-old man, 70 kg and 175 cm, has BMR = 700 + 1,093.75 − 150 + 5 = 1,648.75 kcal. At a moderate activity multiplier of 1.55, maintenance is 1,648.75 × 1.55 = about 2,556 kcal a day. A 500 kcal deficit gives about 2,056 kcal a day for weight loss at roughly half a kilogram a week in simple energy terms.
How to use this calculator
- Choose metric or imperial units and enter your sex and age.
- Enter your weight and height.
- Pick the activity level that matches your average week.
- Read your maintenance calories in the headline panel.
- Use the goal table to see maintain, loss and gain targets, and the deep table to compare every activity level.
Why estimates drift, and what to do about it
Two people with identical inputs can burn noticeably different amounts. Muscle burns more at rest than fat, some medicines and health conditions change energy use, and daily movement outside exercise, sometimes called NEAT, varies hugely between jobs and lifestyles. Food tracking also has error: labels allow a margin, portions are guessed, and cooking changes water content and therefore calories per bite.
That is why the trend matters more than the formula. Weigh yourself a few times a week under similar conditions, look at the average over several weeks, and adjust your target in small steps. If you feel unwell, are pregnant, are recovering from illness, or have a history of disordered eating, skip calorie targets altogether and talk to a qualified professional. This calculator supports general planning only and is not medical advice.
Important note
For information only — not medical advice. This calculator uses standard published formulas to estimate values for general education and planning. It does not diagnose, treat, or replace the advice of a doctor or other qualified health professional. If you have a health concern, are pregnant, or are making decisions about treatment, medication, or a major diet or exercise change, please talk to a healthcare professional first.