Understanding Fabric Yardage

Husband and I recently upgraded to a king sized mattress. Why we waited so long, I have no idea. It is simply heaven! We used to think the queen was so nice because we could sleep near each other and be close. I guess that's what ten years will do to you...we are very happy on our opposite sides of the equator now!

Anywho, I was hoping to purchase an upholstered bed and headboard unit, but I can't find anything I love and we need a headboard. I keep losing my pillows behind the bed. So after reading several tutorials, I convinced the husband to make a headboard with me this weekend until we can find something we love (or maybe until we move into our forever house).

Here are the tutorials for anyone that might be interested in embarking on a similar project: Centsational Girl, Pink Wallpaper, Design*Sponge and Freckles Chick.

The goal is to make a headboard with this shape

and cover it with this fabric - Braemore/P. Kaufmann's Fioretto in Sandstone, which runs in a 54" width with a vertical repeat of 25.25"and a 9" horizontal repeat.

Before we cut any of the curves on our plywood, the wood will be 72" wide x 48" high. So in my head we would need 2 1/2 yards of fabric to create this headboard. Right? 

I'm tempted to build legs for the headboard too so that the headboard doesn't just hang there. So perhaps 3 yards would be better? 

I used an online yardage chart and it told me to buy 6 1/2 yards (insane). I'm thinking this is for people who create a full slipcover or something. But what do I care what the back looks like??

What do you think? Will 3 yards be enough? Thanks in advance!