The Harris Benedict BMR calculator calculates the minimum amount of calories you need to maintain your weight as well as perform your day to day activities based on sex, age, height and weight.
The formula used is the Harris Benedict Formula and is only an approximate estimate but it gives you a starting point. More on this formula later.
First of all please complete the form here to get an approximate BMR figure. (conversion charts are below if you need them). Then continue below for further instructions.
Important Note : Do not input your height in ‘Feet and Inches’. Input your height in TOTAL inches. See the convertor below if you’re unsure what your height is in TOTAL inches
HEIGHT + WEIGHT CONVERTORS
(the figure in the red column goes into the calculator)
Note : If you are any heavier/lighter than the range given in the ‘weight’ conversion chart just add/subtract 3.15kg for every half stone or 7lbs over/under you are. For example if you are 14.5 stone (or 203lbs) you’d be 92.15kg.
NOW YOU HAVE YOUR BMR…
You’re nearly finished. We just have to look at how active you are in your lifestyle to get a true representation of how many calories you will need to maintain your weight. We’ll now find your total daily energy expenditure or your TDEE.
|How much exercise do you do?||TDEE – TOTAL DAILY EXPENDITURE|
|Sedentary (Office Job – Not very active)||BMR X 1.2|
|Lightly Active (1-3 days/wk light exercise)||BMR X 1.375|
|Moderately Active (moderate exercise 3-5 days/wk)||BMR X 1.55|
|Very Active (intense exercise 5-7 days/wk)||BMR X 1.725|
|Over Active (Hard exercise daily. Active job. Training for sports contest/competition)||BMR X 1.9|
The calculator determined my Basal Metabolic Rate to be 1818. I’d say I’m only lightly active recently which would mean that I multiply that figure by 1.375.
1818 x 1.375 = 2490 calories is the amount of calories I need to maintain my weight
Now that you know your Total Daily Energy Expenditure..
|Build Muscle||OR||Lose Weight/Burn Fat|
|If your goal is to build muscle, you should start by eating 500 caloriesover what your Total Daily Energy Expenditure is.|
Expect to gain 1-2 kgs per week when you’re starting out. 0.5-1 kgs if you’re a veteran. Any more than this and you’re probably gaining too much fat and you’ll need to reduce calories slightly.
If you aren’t noticing any weight gain on an extra 500 calories, try gradually increasing the number to 1000 calories on top of your TDEE.
|If your goal is to burn fat and lose weight, you should start by eating 500 calories less than your TDEE.|
Expect to lose 0.5-1kg a week (1-2lbs). If you’re losing any more than this, it is likely coming from muscle tissue. This will slow your metabolism down and make it harder to lose weight in the long run!
If you aren’t noticing any weight loss, decrease your calories by a further 250 a week until you see the weight dropping OR increase your training frequency and intensity
Important Note : Remember that not all calories are created equal! A 3000 calorie diet consisting of mainly junk food and saturated fats is NOT the same as a 3000 calorie diet consisting of protein, complex carbs and essential fats.
The Harris Benedict Formula is pretty accurate for all but the really muscular physiques (it will underestimate your calorie requirements) and the really overweight (it will overestimate your requirements).
If you find yourself in the latter situation, it would be wise to find out your LBM – Lean body mass. You can do this by getting a body fat check.
Then, take your LBM and add 10% to it. Then put that figure into the calculator for a closer estimate for what your daily calorie needs are.
For example if my LBM was 67kg, I’d add 10% to it. 67 + 6.7 = 73.7kg and I’d put that into the calculator.
If you fancy doing the math all on your own, there is a more accurate formula than the Harris Benedict Formula that takes Lean Body Mass into account. It’s called
The Katch-Mcardle Formula
This formula is more accurate for everybody but you’ll have to know your LBM first. The formula works for both men and women because no guess work needs to be done with body fat levels once you’ve obtained your lean body mass.
BMR = 370 + (21.6 X lean body mass in kg)
I’m 74kg in total weight
I have a body fat % of 12%
So my lean weight is 65.1 kg
My BMR is 370 + 1406 = 1776 calories (very close to what the Harris Benedict Formula gave me)
Then multiply that figure again depending on your activity level.
So mine would be 1776 calories x 1.375 (lightly active) = 2446 Calories needed to maintain weight
As you can see the difference in results between the Katch Mcardle Formula and the Harris Benedict Formula were negligible for me. If you’re between 10-18% body-fat (higher for women), then the calculator at the top of this page will serve you fine (unless you’re extremely muscular).