Question 1

What is Basal Metabolic Rate (BMR)?

Accepted Answer

BMR is the number of calories your body burns at complete rest to maintain vital functions such as breathing, circulation, temperature regulation, and cell production. It is the baseline of your daily calorie expenditure — the minimum energy your body needs to survive.

Question 2

Which BMR formula does CalcTools AI use?

Accepted Answer

CalcTools AI uses the Mifflin-St Jeor equation (1990), which is recommended by the American Dietetic Association as the most accurate BMR formula for most adults. It accounts for gender, weight, height, and age.

Question 3

What is the difference between BMR and TDEE?

Accepted Answer

BMR is the calories burned at complete rest. TDEE (Total Daily Energy Expenditure) adds your activity level on top — it is the total calories you burn in a day including exercise, work, and all movement. TDEE is the number to use when planning your daily calorie intake.

Question 4

How many calories should I eat to lose weight?

Accepted Answer

To lose approximately 0.5 kg per week, eat 500 kcal below your TDEE per day. This is known as a moderate deficit and is generally considered safe and sustainable. Avoid deficits larger than 1,000 kcal/day without medical guidance, as they can cause muscle loss and nutrient deficiencies.

Question 5

How does age affect BMR?

Accepted Answer

BMR naturally declines with age, primarily because lean muscle mass decreases over time. The Mifflin-St Jeor equation captures this by including age as a negative factor. After age 30, BMR can decrease by approximately 2–3% per decade. Resistance training is one of the most effective ways to slow this decline.

Question 6

Is BMR the same for men and women?

Accepted Answer

No. Men typically have a higher BMR than women at the same weight, height, and age because they tend to carry more lean muscle mass. The Mifflin-St Jeor formula accounts for this with a gender constant: +5 for men and −161 for women.

Question 7

Can I use this calculator if I use pounds and feet?

Accepted Answer

Yes. The BMR Calculator supports both metric (kg, cm) and imperial (lbs, ft & in) inputs. Simply toggle the unit buttons next to the weight and height fields — the calculator converts and computes your BMR and TDEE automatically.

Question 8

Is the BMR Calculator free?

Accepted Answer

Yes, CalcTools AI's BMR Calculator is completely free with no registration required. You can calculate your BMR and TDEE, view your full calorie target table, get an AI-powered insight, and download a PDF report at no cost.

BMR Calculator for 30-Year-Old, 90 kg

Daily Calorie Targets

30-Year-Old, 90 kg

BMR Calculator for 30-Year-Old, 90 kg

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