How much calories do i consume each day if i want to lose 40 lbs?

Its a Formula!: This is the appropriate way to calculate how many calories/day you have to consume. The average loss per week is around 2 pounds/week so you would have 140 days of reduced calories intake (20 weeks x 7 days). 1) subtract goal weight from current weight 2) multiply 40 x 3500=140, 000 3) 140, 000 by 140 equals 1000. For you, it would be 1000 cal/day, which is not healthy. Average is 1400/cal a day.