Article
BMR, basal metabolic rate
BMR estimates the energy the body uses at rest. It is not how much you should eat on a day with work and a walk.
The BMR calculator does this. The full day is on TDEE.
The idea in brief
BMR estimates the energy the body uses at rest: heartbeat, breathing, and heat.
With daily activity the number rises. That larger value is TDEE, total daily energy expenditure. BMR is not a full-day eating target, because a normal day still includes movement.
On this page: BMR is basal metabolic rate: an estimate of energy at rest. TDEE is total daily energy expenditure, which is BMR times an activity factor. Mifflin-St Jeor is the formula on this card. Harris-Benedict is a different resting formula with different constants, so the calorie totals will not match. The unit kcal means kilocalories.
When this helps
| Situation | What the card shows |
|---|---|
| You need a resting base before you add movement on the TDEE page. | The card estimates BMR with the Mifflin formula and does not multiply it by activity yet. |
| You compare two people, or two sets of weight, height, and age. | The formula stays the same. You change weight, height, age, or sex and compare the results. |
| You are looking for how much to eat for a full day. | BMR is rest only. It is not an eating target for a day with work and a walk. |
The Mifflin-St Jeor formula
10 × weight in kg + 6.25 × height in cm - 5 × age, then +5 for a man or -161 for a woman. A man 30/80/180 is 1780 kcal. A woman 28/65/165 is about 1380 kcal. Age subtracts 5 kcal per year.
This is not Harris-Benedict. The constants differ, so another table will not match calorie for calorie. Mifflin is an estimate for adults, not a lab measurement and not advice in pregnancy or for a child.
What to do with it
For a day with movement, multiply BMR by an activity factor on the TDEE card. 1780 × 1.55 is about 2759 kcal. Protein grams come from mass, not from this base. The BMR card stops at one number: rest.
A worked example
A man 30 / 80 kg / 180 cm
10×80 + 6.25×180 - 5×30 + 5 = 1780 kcal. That is rest. At activity 1.55 the day is about 2759 kcal on the TDEE card.
Typical numbers from the card
| Inputs | Result |
|---|---|
| The man is 30 years old, weighs 80 kg, and is 180 cm tall. | BMR is 1780 kcal. |
| The woman is 28 years old, weighs 65 kg, and is 165 cm tall. | BMR is about 1380 kcal. |
| You multiply that 1780 kcal base by 1.55 on the TDEE page. | A day with movement is about 2759 kcal, but that lives on the TDEE page. |
Typical mistakes
| Mistake | What goes wrong | How to avoid it |
|---|---|---|
| You treat BMR as how much you should eat in a day. | This number still has no movement in it. | Count a day with activity on the TDEE page. |
| You compare the result with a Harris-Benedict table. | Those constants are different, so the calorie totals will not match. | This card stays on one Mifflin formula so results can be compared. |
| You use this formula for a child or in pregnancy. | This formula is outside the range of this card. | Mifflin is meant for adults. |
Before you read the base
- Weight, height, age, and sex come from the same set of data.
- The formula is Mifflin-St Jeor, not Harris-Benedict.
- The result is a resting estimate, not medical advice.
- TDEE and protein are on separate cards.
Frequently asked questions
What BMR does a man 30 years, 80 kg, 180 cm have?
1780 kcal from Mifflin. TDEE at 1.55 is about 2759, on a separate page.
Why is a woman 28/65/165 about 1380?
The constant is -161, not +5, and the measurements differ. 10×65 + 6.25×165 - 5×28 - 161 ≈ 1380.
Is BMR how much I should eat?
No. BMR is rest only. The day with activity is TDEE.
Why Mifflin, not Harris-Benedict?
This card stays on one formula so 1780 is comparable. Other constants give another result.
Is this for children?
No. Mifflin is for adults. Pregnancy and nursing use other rules too.
Will weight in pounds work?
You can pick US units in the header. The formula still runs in kg and cm after conversion.