BMR Calculator for Weight Loss

Use this BMR calculator to determine your basal metabolic resting rate. This calculator will tell you the number of calories per day you should consume to maintain your existing weight based on the resting BMR. You can use either the metric or US measurements for this online tool.

Just select your gender and then plug in your weight and height information. Be sure to select the correct measurement for each (pounds or kg for weight and inches or cm for height).

You will be presented with the calories per day based on the input information.

To determine what your daily calorie intake should be in order to start losing weight, you will need to know and understand your basal metabolic rate.

BMR is the amount of calories you would burn while at rest.

Your Basal Metabolic Rate is:

Your Average Daily Calorie Need is:

Activity Level Key for BMR Calculator

Sedentary = Little or no exercise.
Somewhat Active = Light exercise 1 - 3 days a week.
Moderately Active = Moderate exercise or sports 3 - 5 days a week.
Very Active = Hard exercise or sports 6 - 7 days a week.
Extremely Active = Hard daily exercise or sports plus physical job or exercise 2x a day

To understand the calculation used in this BMR calculator, keep reading onto the next sections.

Basal Metabolic Rate Calculation

If you are curious about the math behind this BMR calculator, then be sure to read on to learn more about your basal metabolic rate.

The basal metabolic rate calculation takes into account many different variables. There are different methods used for BMR calculation with the most common calculation being the Harris-Benedict formula.

This formula uses height, weight, age and sex to determine your basal metabolic rate. The results of the BMR calculation using these variables are an estimate, but will be fairly accurate for most people.

Basal Metabolic Calculation Explained

There are several variables that are used in the BMR calculator. These include age, gender, weight and height. These factors are used to determine your resting BMR. Additionally the activity level is used to determine your total daily caloric needs. You may be wondering why and how these variables are used in the BMR calculator.

Well, age plays a role in your metabolic rate. As we age, our metabolism slows down.

I know this doesn't seem fair to those of us over 40, but it's true. Gender also plays a role in the calculation.

Why? Well men tend to have more lean muscle and the more lean muscle you have the higher your basal metaoblic rate.

Lastly, body surface is needed to determine your BMR calculation. This is why both weight and height are used. The more body surface you have, the more calories you burn through your basal metabolic rate.

However, because lean body mass is not a variable in the Harris Benedict formula, it may be inaccurate for those that are extremely muscular as it may underestimate caloric needs. This is because muscles are more metabolically demanding than fat.

It may also be inaccurate for people with an extremely high percentage of body fat, overestimating their caloric needs as your body uses fewer calories to sustain the fat.

Harris-Benedict Formula

As stated above, this BMR calculator is using the Harris-Benedict formula to determine the results. Note that this formula uses kilograms for weight and centimeters for height. Below this formula you will see the conversion factors to use for pounds and inches.

Men: 66 + (13.7 x weight) + (5 x height) - (6.8 x age in years)

Women: 655 + (9.6 x weight) + (1.8 x height) - (4.7 x age in years)

You can also use this google gadget to convert from lb to kg and inches to cm. Just type in your weight followed by lb (or pounds) and then type in the measure you want to convert to (kg). For your height, you can type in feet and inches to convert to cm. Example, type in 5 ft 6 in and in the second box type in cm to convert to centimeters.

Metric to Imperial conversion

1 inch = 2.54 cm

Example, if you are 5’3” (or 63”), then you height in cm equals 63 inches x 2.54 cm = 160 cm

1 pound = .45 kg (1 kg = 2.2 pounds so 1 pound divided by 2.2 kg equals .45)

Example, if you weight 160 pounds, then your weight in kg equals 160 lbs x .45 kg = 72 kg

So, if you are a 40 year old female weighing 150 pounds at 5’3” (or 63 inches), your calculation would be;

655 + (9.6 x [150 lbs x .45 kg]) + (1.8 x [63 inches x 2.54 cm]) – (4.7 x 40)

655 + (9.6 x 68 kg) + (1.8 x 160 cm) – (188)

655 + 653 + 288 – 188 = 1408 calories/day

The Activity Factor

A weight loss calculator will use the results of your basal metabolic rate calculation and then factor in an activity level. This will give you the amount of calories you burn based on the BMR as well as your exercises.

The reason you need to understand the activity factor for this BMR calculator, is you want to ensure you are consuming enough calories for your BMR as well as your level of exercise. By factoring in the activity level in a weight loss calculator you will get the proper daily calorie intake needs to sustain and/or lose weight.

Below is what is used to factor in the activity level.

Exercise/Activity multiplier

Sedentary	BMR x 1.2	no or little exercise
Lightly active	BMR x 1.375	light exercise 1 - 3 days/week
Moderately active	BMR x 1.55	mod. exercise/sports 3 - 5 days/week
Very active	BMR x 1.725	hard exercise/sports 6 - 7 days/week
Extremely active	BMR x 1.9	hard daily exercise/sports plus physical job or exercise 2x a day