Calories; they are everywhere these days. We spend an awful lot of time and energy trying to count how many calories we consume per day, per meal, even per forkful. Yet many of us usually spend little if any time trying to figure out exactly how many calories we actually need, otherwise called our caloric needs.

It’s pretty easy to look up in any number of nutrition tables how many calories a certain food contains. It’s also pretty easy to add up all the calories you have eaten in a day to get your total daily caloric consumption. It’s a little harder to calculate how many you actually need.

So how do you figure that out?

Well there is a standard formula used to estimate your estimated daily caloric needs. It uses a few basic measurements including gender, height, weight, age and activity level to help estimate your daily requirement.

First, you need to calculate your Basal Metabolic Rate (BMR). This is the number of calories you burn daily while at rest. Believe it or not, we burn a majority of our daily calories while at rest (e.g. sitting on the couch watching TV). Your BMR is made up of the energy required to sustain all those vital bodily functions, essential things like breathing, thinking and pumping blood around the body.

The formula to calculate BMR is:
Imperial (lb/in)
Men = 66 + (6.35 x weight lbs) + (12.7 x height ins) – (6.8 x age yrs)
Women = 655 + (4.35 x weight lbs) + (4.7 x height ins) – (4.7 x age yrs)

Metric (kg/cm)
Men = 66 + (13.7 x weight kgs) + (5 x height cm) – (6.8 x age yrs)
Women = 655 + (9.6 x weight kgs) + (1.8 x height cm) – (4.7 x age yrs)

So BMR estimates the calories you burn while at rest. But what if you’re moving around a lot during the day? Now you have to take into account your activity level and assign what’s knows as a Physical Activity coefficient (PA) to the amount of activity you perform. Physical Activity (PA) is categorized into a few different levels:

Sedentary (no exercise, inactive lifestyle) – 1.2
Lightly Active (light exercise such as walking 1-3 days/wk) – 1.375
Moderately Active (moderate exercise 3-5 days/wk) – 1.55
Very Active (long duration hard exercise with heavy exertion 6-7 days/wk)- 1.725
Extra Active (competitive athlete in training) – 1.9

To calculate your total daily caloric needs or your Total Energy Expenditure (TEE) you simply multiply your BMR by your Physcial Activity (PA) level.

BMR x PA = TEE

For example lets take a 40 year old male who is 170lbs, 5′ 9″ and moderately active:
BMR: 66 + (6.35 x 170) + (12.7 x 69) – (6.8 x 40) = 1730
Moderate Activity Level: 1.55
TEE: 1730 x 1.55 = 2682

By estimating how many calories you actually need along with how many you consume you get a much better idea of your daily caloric balance (caloric intake vs. expenditure).