How to measure bar width?
 

I’m looking to put a carbon fiber handlebar on my road bike and found a good deal on an easton, I have the choice of 40, 42, or 44. I would like one a little wider than what I have now. How is it measured, center to center? Thanks!

Depends. Most measure from center to center. but not all. In addition, if there's any flare you need to know if it's measured at the ends or at the top. I'd look up the prospective model on the manufacturer's site and see how it's measured and then measure your existing bars in the same fashion.

I use a tape measure ..... but I am open to alternative methods .....

Thanks Sy Reene that’s perfect