I don't see how this could ever possibly be accurate. How is a rep of a 400 lb squat by a 250 lb lean male comparable to a 5 lb curl by a 110 lb woman??
And even with the same individual, each rep of an exercise will burn more calories depending on the intensity with which it is performed, and how many muscles are involved. My advice is to just ignore weight training as a calorie burning activity (even though it does turn your body into a fat burning furnace). The only reason being that if you're eating properly you will have replaced all the calories you burned during weight training in hours post-workout, so you're breaking even. But in actuality you're not. You're body is repairing itself for 24-36 hours after your session, so it's using calories to do that.
If you're cutting and want to count cals, just eat at maintenance and burn 500 cals a day with cardio. This will allow you to get another 500 calories (~100 grams) worth of protein in as opposed to if you at 500 cals below maintenance and did no cardio.