How much time do I have to spend in hell to earn the "Medium Well" achievement in Super Meat Boy?

So, during the Steam Summer Sale 2011, Super Meat Boy was updated and has a new achievement: "Medium Well". It's description is only, "Spend as little time in hell as possible"

How do I earn this new achievement?

Unless I messed up with my calculator, the A+'s for each level in hell put you at a time total of 631.8 seconds.

Update: Super Meat Boy was later updated in 2011-07-20 and what was originally the "Medium Rare" achievement has now been renamed to "Medium Well".


The SMB team has said on Twitter that it counts a sum of the best play times in Hell.

From the Super Meat Boy Forums:

You must clear Hell, both light and dark world

The sum of your best times in Hell must be less than some threshold

Apparently, the threshold is 500 seconds.