BMR vs TDEE Calculator
BMR and TDEE are the two calorie numbers most people meet first when planning nutrition: basal metabolic rate estimates the energy your body uses at rest, while total daily energy expenditure estimates the full day including movement and exercise. The site’s two calculators start from the same equation family — both use the Mifflin-St Jeor equation and the same activity factors — but they make different results primary. The BMR calculator centers the resting estimate and shows two equations; the TDEE calculator centers maintenance calories and adds mild deficit and surplus targets.
Because the underlying math matches when the inputs match, this comparison is really about which output you need: the resting floor with an equation comparison, or the full-day estimate with planning targets. This page is informational, not medical advice, and neither calculator measures your actual metabolism.
What each calculator does
The BMR calculator takes sex, age, height, and weight. Its primary result is Mifflin-St Jeor BMR rounded to whole calories per day, and it also displays the older Harris-Benedict equation as a secondary value. It then estimates TDEE by multiplying the Mifflin-St Jeor result by a selected activity factor: 1.2 sedentary, 1.375 light, 1.55 moderate, 1.725 very active, or 1.9 extra active. For a male, age 30, 180 cm, 75 kg, sedentary, it shows Mifflin-St Jeor at 1,730 kcal/day, Harris-Benedict at about 1,796 kcal/day, and sedentary TDEE at 2,076 kcal/day.
The TDEE calculator takes the same four inputs plus an activity level and makes total daily energy expenditure the primary result. It computes the same Mifflin-St Jeor BMR, multiplies by the same activity factors (labeled sedentary 1.2 through very active 1.9), and then shows mild targets: 10% below TDEE as a deficit and 10% above as a surplus, all rounded to whole calories. For a male, age 30, 175 cm, 70 kg, moderate, it shows BMR 1,649 kcal/day, maintenance 2,556 kcal/day, a mild deficit of 2,300, and a mild surplus of 2,811.
Side-by-side comparison
| Feature | BMR calculator | TDEE calculator |
|---|---|---|
| Inputs | Sex, age, height, weight | Sex, age, height, weight, activity level |
| Primary result | Mifflin-St Jeor BMR (resting estimate) | TDEE / maintenance calories |
| Secondary results | Harris-Benedict BMR; one activity-adjusted TDEE | Mild 10% deficit and 10% surplus targets |
| Equation basis | Mifflin-St Jeor primary, Harris-Benedict for comparison | Mifflin-St Jeor only |
| Activity factors | 1.2 to 1.9 (five steps) | 1.2 to 1.9 (five steps) |
| Planning outputs | None beyond TDEE | Deficit and surplus calorie targets |
| Typical example | Male 30, 180 cm, 75 kg, sedentary: BMR 1,730, TDEE 2,076 | Male 30, 175 cm, 70 kg, moderate: BMR 1,649, maintenance 2,556 |
When to use which
Use the BMR calculator when your question is about the resting estimate itself: comparing the Mifflin-St Jeor and Harris-Benedict equations, or checking how the activity factor scales one resting number into a daily estimate. Its own guidance warns that BMR is below most people’s total needs, so it should not be treated as a recommended intake.
Use the TDEE calculator when your question is about the full day: what maintenance roughly looks like, and what mild deficit and surplus starting points follow from it. It is the more planning-oriented tool, with the same arithmetic underneath.
Both pages stress the same limits: the equations predict population averages, the activity factor is a guess you supply, and the practical check is comparing the estimate with consistent intake records and weight trends over time. When two calculators agree on inputs, differences in output come from scope — resting estimate versus full-day estimate — not from different math.
Where to start
- BMR calculator — resting estimate with Mifflin-St Jeor primary, Harris-Benedict comparison, and one activity-adjusted TDEE.
- TDEE calculator — maintenance calories as the primary result with mild 10% deficit and surplus targets.
Informational note: This page is an educational comparison, not medical advice. BMR and TDEE estimates come from population equations and do not measure your metabolism; body composition, thyroid status, medications, illness, training load, and tracking accuracy can all shift real energy needs. Ask a clinician or registered dietitian for individualized assessment, especially with unexplained weight change, chronic illness, pregnancy, adolescence, or an eating disorder history.