Here is how to calculate your daily calorie deficiency.
Calculate your Basal Metabolic Rate (BMR), multiply your BMR by 1.2 to 1.9 depending on your Activity Level (AL), add your Calories Burned (CB) for the day, and then subtract your Daily Calorie Intake (DCI) for the day to get your Calorie Deficiency (CD) for the day.
Here is the formula: CD = (BMR x AL) + WCB – DCI. My BMR is 1603 and I have a deskjob so my AL is 1.2, my WCB today was 752 and my DCI was 1000. So (1603BMR x 1.2AL) + 752CB – 1000DCI = 1675CD.
You can calculate your daily Weight Loss by taking your Calorie Deficient (CD) and divided it by Calories Per Pound (CPLB) which is 3500. Here is the formula WL = CD/3500. So 1675CD / 3500CPLB = 0.47LB.
There are a number of equations that estimate your BMR. The Harris-Benedict equation was devised in 1919, in 1990 the Mifflin-ST St Jeor equation which is consider better was devised. Currently there is a more accurate formula called the Katch-McArdle equation but it is based on lean body mass (LBM) which you need to know your Body Fat Percent (BFP) to calculate.
I have a bathroom scale that gives me my BFP from which I can calculate my LBM. The formula for LBM is your 100 minus your BFP times your weight (W). So LBM = (100 – BFP) x W.
After you come up with your BMR you need to multiply it by your Activity Level (AL). The AL value that is used is between 1.2 and 1.9). I use 1.2 because I have a deskjob and then add my Calories Burned (CB) as a separate number as you see in my above formula.
Here Are Some Tools:
Ideal Weight Calculation Tool — Provides the Ideal Weight Calculation using the Hamwi, Robinson, Miller, and BMI based calculations.
Daily Calorie Needs — Provides BMR using the Mifflin-St Jeor, Katch-McArdle, and Harris-Benedict based calculations. This tool also takes your Activity Level (AL) into consideration.