Labor vs Material cost

[Christine Edwards]

I had a contractor give me an estimate for some work that needs to be done on my house.

Material cost  $15,345

From what I have read online, it says that labor should be roughly around 40 - 50% of the total project cost.  Is this true?  

If so,  could I double the materials to come up with a rough estimate of what labor should be?

If not, is there a way to estimate the total project cost based on materials.  I understand it wouldn't be exact, but I got an estimate where labor costs ended up being about 71% of total cost.  Which is crazy high to me.

Any advice/experience would be great.

Thank You

Christine