I'm making a cake that requires two 12x17x3" sheet cakes end to end for a landing strip, how many batches of the MFF should I make?

Curious to see what everyone else says. I just made 2 batches last week of chocolate mmf to cover a 12" and a 9" cake. I guess, if you try to calculate the area you need to cover, you may need to make 4 batches.

Bump,

How much do I need for a 6"x4 , 8"x8 and 10"x4, all round cakes?

The Wilton site has a handy chart to follow.

Each batch of MFF makes about 5 pounds for me - everybody could be a little different but pretty close to that. The 2 12x18's would take about 2 batches and it would be close so if you roll much thicker than I do you might need a smidge more. The 6, 8 & 10's would take 1 recipe. I don't make mmf so I can't help with that. HTH

A batch of MMF uses two pound of powdered sugar and a pound of marshmallows, so that's a three-pound (or so) batch.

Thank you for helping me out, it gives me an idea on how much to make.
I was thinking more like 4... So, I'm making 3.
I just made the first batch and I only got 3.75 pounds. Maybe tomorrow I will have to add more sugar.
I will post the "final answer" when I'm done.