Bolt Size - Imperial/Metric

[pcmRAAR9]

Hi. Does anyone have information for bolt size conversion unit from imperial to metric? Example if using asme, bolt size shown as 1/2", 3/4", etc but my client want to know as Mxx (M12, etc). Any reference?
I've done one project, the bolt size in Data Manager shown as 1/2", 5/8", 3/4", 7/8", so what is this unit in Mxx?

I used ALLPASTENER brochure as reference but got problem. i've checked one size 7/8" in P3D and its M22 (brochure), but when i look at the iso, it stated M24. 

Now i'm confuse which one is correct. Please help 

[h_eger]

Dear @pcmRAAR9 ,

I work with this list