Macro series part 2: How to calculate macros

In Part 1 of the macros series I outlined what is meant by ‘macros’ and how important each macronutrient is. I recommend reading this article first. In Part 2 I am going to explain how you can easily calculate your macros. That is how much protein, fat and carbohydrates your body needs.

4 steps to calculate your macros

Calculate your ‘maintenance’ macros

These are the calories you need to eat each day to maintain your current weight.

  1. Start by calculating your Basal Metabolic Rate (BMR) – this is the amount of calories you would burn by simply being alive but staying in bed all day. I recommend the Harris-Benedict equation:

Females: 655 + ( 9.6 x weight in kilos ) + ( 1.8 x height in cm ) – ( 4.7 x age in years )

Males: 66 + ( 13.7 x weight in kilos ) + ( 5 x height in cm ) – ( 6.8 x age in years )

2. The next step is to add a ‘activity multiplier’ to your BMR to reflect the amount of activity you do.

  • Sedentary (little or no exercise): BMR x 1.2
  • Lightly active (easy exercise/sports 1-3 days/week): BMR x 1.375
  • Moderately active (moderate exercise/sports 3-5 days/week): BMR x 1.55
  • Very active (hard exercise/sports 6-7 days a week): BMR x 1.725
  • Extremely active (very hard exercise/sports and physical job): BMR x 1.9

This end number is the amount of calories your body needs each day based on your individual BMR and how active your lifestyle is in order to maintain your current weight.

Calculating your macro split

This section will explain how you calculate your protein, carbohydrate and fat needs.


You need 1g of protein per 1lb of bodyweight. So, if you weigh 146lb you need 146g of protein. If you have a very active lifestyle you may want to increase this to 1.5/2g of protein per 1lb of bodyweight. There are 4 calories for every 1g of protein.


You need 0.3g to 0.6g of fat per 1lb of bodyweight. The number you choose may be based on trial and error as you find out what your body prefers. For example, I know my body prefers less fat and more carbohydrate, so I would choose 0.3g per pound of bodyweight. There are 9 calories for every 1g of fat.


In order to calculate the number of carbohydrates you need, you first have to do a few other calculations.

  1. Calculate your protein need in calories: 4 x g of protein = calories of protein
  2. Calculate your fat need in calories: 9 x g of fat = calories of fat
  3. Add these two numbers together
  4. Subtract this from your overall calorie needs that you calculated earlier

This number is the amount of calories you require from carbohydrates. In order to find out what this is in grams you need to divide it by 4 (the number of calories in 1g of carbohydrate).

What you have left is your final macro split!

Example macro calculation

Penny is 32, 5 foot 9 and weighs 152lbs. Penny works as lawyer and is mostly sat behind a desk all day. She currently goes for a 30 minute run three times a week.

Her calculations are:

  • BMR = 655 + ( 9.6 x 68.9 ) + ( 1.8 x 179.8 ) – ( 4.7 x 32 )
  • BMR = 655 + (661.44) + (323.64) – (150.4)
  • BMR = 1489.64
  • Maintenance calories = 1489.64 x 1.375
  • Maintenance calories = 2,048
  • Protein = 152g and 608 calories (152 x 4)
  • Fat = 46g and 414 calories (46 x 9)
  • Carbohydrates:
    • 608 + 414 = 1022
    • 2048 – 1022 = 1026 calories of carbohydrate
    • 1026\4 = 257g of carbohydrates

What are you thoughts on calculating macros?

Many people are surprised when they calculate their own macros and realise they have may have spent days of the week under eating followed by other days (usually Friday- Sunday) over eating!

How do I calculate macros for fat loss and muscle building?

Part 3 of the Macro Series will explain exactly how you can manipulate your macros to lose fat or gain muscle, depending on what your goals are. Don’t miss out! Subscribe to my site now and also receive my ‘Steps to Success’ e-book.



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