Does anyone know how accurate the Singapore Math placement tests are for actual US grade equivalency? If so, do you know what grade level 1A and 1B would be?

It's explain somewhere on their website.
1A is 1st grade
1B and 2A are 2nd grade
2B and 3A are 3rd grade
and so on

I found it. Here you go
http://www.singaporemath.com/Placement_Guide_s/85.htm

Thanks LMom! I read that earlier, but I'm trying to find out if anyone knows how closely it correlates to an actual grade-level curriculum. I know curricula vary from state to state and even county to county, but generally speaking, has anyone found their website's chart to be true to scale?

My opinion is that Singapore math is 6 months to a year beyond the typical US placement. So a grade 3 US program will be roughly equivalent to a Singapore math 2A/B. The material is presented differently, so it's not exactly apples to apples.

Agree, 6 months or maybe a little more ahead of US.

I think it would be really difficult to make a straight comparison... They only have six years of arithmetic before they start Algebra and Geometry in mid-7th, so to that extent you could say they're two years ahead of a 9th-grade-algebra scope and sequence, but then again the 9th grade timing isn't as standard as it might have been in the past...

I think in 1st grade the difference is minimal, but it grows along the way. The tests are very true to the Singaporean scope and sequence (so they're reliable for placement) but if you're switching between curricula many people find that their kids place way WAY back just because of the different approach and order of topics, and then they catch up fast. So based on that I'd say it's just hard to compare.

If you needed a US curriculum placement, you could try to find a Saxon placement test... it might be closer.