How to calculate your calories

June 8, 2023 Leah Rose

There are lots of calorie calculators online and in apps, but how do you work out your calories if you want to do it yourself?

You can never know for sure exactly how many calories you need, and it will vary from day to day and week to week - no calculation, whether in an app, online, or done yourself, can ever be 100% accurate.

However, there are ways of making an educated guess or having a pretty good stab at it. Here’s how…

Let’s start by clarifying a few things:

Your goal:
1. To maintain your current weight (your maintenance calories), you need to eat the same amount of calories you are using
2. To lose body fat you need to eat less than your maintenance calories (a calorie deficit)
3. To gain body fat you need to eat more than your maintenance calories (a calorie surplus)
Your activity level
1. The more active you are, the more calories you will use and therefore the more calories you need in order to maintain your current bodyweight. This is going to vary a lot from person to person.
Your timeframe
1. This mainly applies to weight loss - If your goal has a timeframe attached to it then this will affect the size of the calorie deficit you need to create - the bigger the deficit, the quicker the fat loss.

First, you need to calculate your BMR. There are lots of equations available that do this with varying degrees of accuracy depending on your requirement - that’s something to let your coach drill into. For now, here’s the most simple one (it’s Martin MacDonald’s MacMet Method):

Start with this:

Bodyweight in kg x 22 (females)

Bodyweight in kg x 24 (males)

Then, multiply your answer by your physical activity level (PAL) to take into account how much energy you might be using on top of your BMR. Again, normally this is something you let you coach work out because it takes experience to get a feel for this. For now, here’s a simplified guide:

1.1 Sedentary (spend most of every day seated)

1.3 Quite active (active day job that doesn’t involve lots of sitting)

1.5 Active (physical day job)

So, for example if you are a 60kg active female:

60 x 22 x 1.5 = 1980 calories per day (remember this is an estimate and the actual number will vary from person to person)

If you are an 80kg moderately active male:

80 x 24 x 1.5 = 2880 (remember this is an estimate and the actual number will vary from person to person)

Now, adjust your figures to take into account your goals and your activity level. If you want to stay as you are then you don’t need to change the number of calories you have calculated; if you want to lose weight then you need to reduce it; if you like to eat in a slight calorie surplus to gain muscle then you need to increase it.

It’s super important to remember to view the estimated number of calories you need to consume with flexibility, because, well - life.

It can be helpful to think about it like this - the number of calories you need each day is an average. Multiply by 7 to give you a rough idea of how many calories you need on average each week to maintain your current weight. Then, plan days in the week so you have some higher and some lower calorie days depending on what you’re up to and how you’re feeling - to give you flexibility. You do not need to eat the same number of calories every day.

Lastly, monitor your progress in terms of your body weight, your performance and how you feel - over time this will enable you to work out much more accurately what your individual calorie requirements really are. Remember that calorie tracking is a tool to help you achieve your goals and learn new habits, and there is definitely a place for it - but it’s not a way of life.