How many calories?

Follow the feeding guidelines on the bag.  Its just a guideline though, you will know if your dog need more or less than that. 
 
I dont know how accurate this is but its all I could find not based on a specific food.
 
[linkageName=/calculate/der.asp]http://www.petdiets.com/default.asp?Menu=Nutrition&Submenu=DER&ageName=/calculate/der.asp[/link]>http://www.petdiets.com/default.asp?Menu=Nutrition&Submenu=DER&ageName=/calculate/der.asp]http://www.petdiets.com/default.asp?Menu=Nutrition&Submenu=DER&ageName=/calculate/der.asp[/link]

Well, there is a formula for figuring your dogs energy needs.
 
First you have to convert their weight to kilograms. (lbs divided by 2.2) This will give you the weight in kg.
 
Then you need to figure the BMR (basil metabolic rate) which is the amount of kcals your dog needs just to live (breathing, heartbeat). To figure this you do the following (this is algebra):
70(kg^.75)  This will give you the BMR
 
Then, you need to figure your dogs energy factor. This factor is then multiplied by the BMR. If your dog is not a growing puppy, this is your dogs total kcal requirement per day.
Use the following chart to figure energy factor (this would be your dogs activity level)
Sedate = 1.1 - 1.3
Low = 1.4 - 1.5
Moderate = 1.6 - 1.7
High = 1.8
Body building (lactating or recovering) = 2.2 -3.0
 
For example (numbers are hypothetical)
 
BMR = 342
EF = 1.6
 
Total kcals for the day would be:
547.2
 
Now, if your dog has a growth factor (a puppy) you need to do an additional calculation. The growth factor is a constant of 1.5. So you would need to figure the total kcals for the day and multiply that by 1.5, like this:
 
547.2 x 1.5 = 820.8
 
This is now the total kcals YOUR dog requires for the day.
 
If you need any clarification on this, let me know, []

I use this calculatorhttp://www.mycockerspaniel.com/mer.htm

I've got calorie ranges in my dog cookbook, if you want to tell me how much your dog roughly should weigh I'll look it up for you. 

He is a 70 lbs American bulldog. Thanks
 

For 70 lb adult dog--1,471-1,766
 
Now, this is only a range and if you've got a dog whose not super active or tends to put on weight easily,  it's probably going to be too high.
 
For example--Willow is 50 lbs., they give a range of 1,143-1,372. 
 
First, she could never eat enough in one day to make up this many calories, she's just not a big eater.  Second, when I spoke with the vet, she said that 800-1000 calories a day is what we should shoot for.  So, it's just a rough range.
 

Wow, I went to the next page on that food calculator and my 18 pound Jen dog would be eating 6.7 cups of Nutro Max.  47 pound Ben in the medium range of working dogs would be eating 7!  They actually both eat about 2 cups of premium food each, plus 2 pounds of rmb, etc., or Ben often eats from 4 to 6 pounds of rmb (prey model, a whole rabbit, duck, or whatever).

I noticed the same thing, Becca, and my vet agreed with me that the dog food bags list the requirements way higher than the dog usually needs. It seems that Max (at 63 lbs.) *should be* eating about 5 or 6 cups a day, yet he's doing quite nicely on 1-1/2 to 2 cups.  Maybe they just want us to give the dogs more (thus wasting a lot of it) so we'll buy it more often.

Joyce