USA = JAPANESE grit chart?

[Zeasor]

I found the following grit equivalence chart. Anyone know if it is accurate?

USA=Grit=Japanese
100======150
180======240
240======280
280======360
320======500
350======600
500=====1000
600=====1200
700=====2000
900=====4000
1200====5000
1600====6000
2200====8000

 

[Buck268]

Doesn't match with the chart I saved from a post on this board about a year ago. Couldn't say which is right or wrong, though.