Metric Grade Standard

How does the metric grade system for bolts compare to the standard?? I see in the local hardware store, that most metric is 8.8. I know this cant be the same as a grade 8 fastener, but is it close?? Or more like grade 3.

http://www.4x4wire.com/tech/screws/Grade_Class_Properties_Identification.jpg

Grade 8.8 has a Proof Load of 85kspi, Minumum Yield Strength of 92kpsi and Minimum Tensile Strength of 120kpsi. The above link will tell you more, and show you what the markings mean on most bolt heads.

-Rich

Rule of thumb (not exact), grade 5 US = 8.8 metric. Grade 8 US = 10.9 metric.

Matt