# BMR and TDEE: how many calories your body burns before you lift a finger

> Most of the energy you burn each day goes on staying alive, not on workouts. This guide explains BMR, activity multipliers and TDEE with a worked example, shows how the common formulas compare, and what a calorie target can and cannot tell you.

Published 2026-10-08 by Toolcloak. 4 minute read. Original: https://toolcloak.pages.dev/articles/bmr-and-tdee-how-many-calories-your-body-burns-before-you-lift-a-finger
Related free tool: [BMR & Calorie Calculator](https://toolcloak.pages.dev/tools/bmr-calorie-calculator)

Even if you spent the entire day in bed, your body would burn roughly a thousand to two thousand calories keeping your heart beating, lungs working and temperature steady. That resting cost is your **basal metabolic rate (BMR)**. Add movement and digestion and you get your **total daily energy expenditure (TDEE)**, the figure most calorie plans are built on.

> **In short**
> - **BMR** is the energy needed at complete rest. **TDEE = BMR × an activity factor** (1.2 for a desk job up to about 1.9 for very hard training).
> - The Mifflin-St Jeor formula for a 30-year-old man of 75 kg and 175 cm gives a BMR of **1,699 kcal**, and about **2,633 kcal** with moderate exercise.
> - Every formula is an **estimate, often within ±10%**. Treat it as a starting point and adjust from real results over 2 to 3 weeks.
> - Roughly **60–70% of daily energy** goes on BMR, about 10% on digesting food and the rest on movement.

## Where your energy actually goes

People often assume exercise is the main part of their daily burn. For most people it is not. Staying alive costs the most, followed by day-to-day movement such as walking, standing and fidgeting, then deliberate exercise, and finally the cost of digesting food itself.

**A typical split of daily energy use**

|  | Share |
| --- | --- |
| Basal metabolism (BMR) | ≈ 60–70% |
| Daily movement and exercise | ≈ 20–30% |
| Digesting food | ≈ 10% |

*These shares are typical ranges, not exact. A very active person has a bigger movement slice; an older or smaller person has a smaller BMR slice.*

Try it: [BMR & Calorie Calculator](https://toolcloak.pages.dev/tools/bmr-calorie-calculator). Enter age, height, weight and activity level and get BMR, TDEE and example targets.

## The formula, with real numbers

The most widely used equation today is Mifflin-St Jeor (1990). It uses weight in kilograms, height in centimetres and age in years.

> **Mifflin-St Jeor:** Men: BMR = 10 × weight + 6.25 × height − 5 × age + 5. Women: BMR = 10 × weight + 6.25 × height − 5 × age − 161. The only difference between the two is the constant at the end: +5 versus −161.

**Building the BMR of a 30-year-old man (75 kg, 175 cm)**

| Step | Amount |
| --- | --- |
| Weight term (10 × 75) | 750 |
| Height term (6.25 × 175) | +1,094 |
| Age term (5 × 30) | −150 |
| Constant | +5 |
| BMR | 1,699 |

*750 + 1,093.75 − 150 + 5 = 1,699 kcal a day at rest. For a 30-year-old woman of 62 kg and 162 cm the same steps give about 1,322 kcal.*

**Two formulas, same man**

|  | kcal per day |
| --- | --- |
| Mifflin-St Jeor | 1,699 |
| Harris-Benedict (revised) | 1,763 |

*The older Harris-Benedict equation (revised in 1984) gives about 64 kcal more, a gap of roughly 4%. Real people differ from both by a similar margin.*

## From BMR to TDEE

To include daily movement, multiply BMR by an activity factor. The factors are rough averages, and most people choose a level that is too high.

**TDEE for the same man at each activity level (kcal)**

|  | TDEE |
| --- | --- |
| Desk job, little exercise (×1.2) | 2,039 |
| Light exercise 1–3 days (×1.375) | 2,336 |
| Moderate exercise 3–5 days (×1.55) | 2,633 |
| Hard exercise 6–7 days (×1.725) | 2,930 |
| Physical job plus training (×1.9) | 3,228 |

*Same body, different lives: the difference between a desk job and a physical job with training is about 1,200 kcal a day.*

> **Pick the lower level when unsure:** Workouts last an hour, but the other 23 hours matter just as much. If you sit most of the day, “light activity” is usually more honest than “moderate”. Choose the lower level and check against real results.

## Turning TDEE into a plan

Eating about as much as your TDEE keeps weight roughly stable. Eating more leads to gradual gain; eating less to gradual loss. A commonly quoted rule of thumb is that about 7,700 kcal is one kilogram of body weight, so a daily gap of 500 kcal is a bit under half a kilogram a week. Real bodies adapt, so the figure is a guide, not a promise.

**A moderate gap relative to maintenance (the 75 kg man at TDEE ≈ 2,633)**

| Zone | From | To |
| --- | --- | --- |
| Large cut | 70 | 80 |
| Moderate cut | 80 | 95 |
| Maintain | 95 | 105 |
| Gain | 105 | 130 |

*Values are the percentage of TDEE eaten. A cut of 10 to 20% is generally considered moderate. Very large cuts are harder to keep up and are best planned with a doctor or dietitian.*

**A sensible way to use the estimate**

1. **Estimate TDEE.** Use the calculator with an honest activity level.
2. **Track for 2–3 weeks.** Eat roughly that amount and weigh yourself at the same time each week.
3. **Adjust by 5–10%.** If weight moved the wrong way, change intake slightly and repeat. The trend is the real answer.

> **An estimate is not a prescription:** These formulas ignore muscle mass, illness, medication, pregnancy and many other things. They are unsuitable for children and for people with medical conditions or a history of disordered eating. If any of those apply, plan with a doctor or registered dietitian rather than a calculator.

## Why two people of the same weight can differ

**What moves your BMR up or down**

| Box | What it means |
| --- | --- |
| Muscle mass | Muscle burns more at rest than fat. More lean mass raises BMR. |
| Age | The formula subtracts about 5 kcal for each year, partly from lost muscle. |
| Body size | Bigger bodies burn more simply because they have more tissue to run. |
| Sleep and health | Illness and fever raise it; long-term severe under-eating can lower it. |

*This is why a formula can be 10% off for a particular person even when the inputs are right.*

## Quick practice

1. BMR for a 40-year-old man, 80 kg, 180 cm? 800 + 1,125 − 200 + 5 = **1,730 kcal**.
2. TDEE with light exercise (×1.375)? 1,730 × 1.375 ≈ **2,379 kcal**.
3. If someone eats 2,000 kcal against a TDEE of 2,400, what is the daily gap? **400 kcal**, or about 17%.
4. Why can two people with the same BMR gain and lose weight differently? **Different movement, digestion, sleep and measurement error.**

Pair the calorie estimate with other numbers: [BMI](https://toolcloak.pages.dev/articles/what-your-bmi-can-tell-you-and-what-it-cannot) for a rough weight check, [heart rate zones](https://toolcloak.pages.dev/articles/heart-rate-zones-explained-what-each-of-the-five-zones-is-for) for training, and [sleep cycles](https://toolcloak.pages.dev/articles/sleep-in-90-minute-cycles-when-to-go-to-bed) for recovery.

## Frequently asked questions

### What is BMR?

Basal metabolic rate is the energy your body needs at complete rest to keep you alive, mostly breathing, circulation, temperature control and cell repair.

### What is the difference between BMR and TDEE?

BMR is energy at rest. TDEE adds daily movement, exercise and digesting food, so it is always higher.

### Which BMR formula is the best?

Mifflin-St Jeor is widely recommended for the general population. The Katch-McArdle formula can be better when body fat is known. None is accurate for everyone.

### How many calories should I eat to lose weight?

A moderate gap of 10 to 20% below your TDEE is common. The best number depends on health, age and goals, so check with a professional for anything larger.

### Does muscle really raise BMR?

Yes, but modestly. A kilogram of muscle burns only a few more calories at rest than a kilogram of fat, so the effect is real but small.

### Are calorie calculators accurate?

They are estimates, usually within about 10%. Use the result as a starting point and adjust from how your weight changes over a few weeks.