JEFIT

I use Jefit as well, and you've got a couple of options...

First, you could add it as a Cardio activity, and search for "Strength training". Why it's listed under Cardio is beyond me, but it's there.

A 2nd option is to add it as a custom exercise and work out the calorie burn estimate yourself.

A 3rd option is to search through the Strength activities for similar exercises, and go with those estimates. That strikes me as a humongous pain in the a__ though.

And finally, the probably-over-complicated way that I do it: I use Digifit, linked to Fitbit, which is linked to MFP. I also use the Compendium of Physical Activities to estimate calorie burn for strength/resistance training, put that estimate into Digifit, which sends exercise calories burned data to Fitbit, and then those numbers are rolled into my Fitbit calorie adjustment every day.

My experience is that the MFP "Cardio / Strength training" calorie burn estimate is pretty accurate, and maybe just a bit low, which is good if you want to err on the side of caution, and that's definitely your easiest route.

Search for "strength" under Cardio activity: http://www.myfitnesspal.com/exercise/add_to_diary?type=cardio

It's just a generic placeholder.

Or you can search for more specific exercises under Strength activity: http://www.myfitnesspal.com/exercise/add_to_diary?type=strength

For example, search for "curl" to see some options.

For me, though, adding one exercise at a time is too time consuming.