What is the 20bb push/fold range? (heads-up)

At 20bb heads-up, the small blind open-shoves 40% of hands and the big blind calls a shove with 20.5%.

Twenty big blinds is the top of the push/fold zone. Beyond this depth, open-raising and playing postflop generally beats jamming, because you have enough chips to apply pressure across streets without risking your whole stack every hand. At exactly 20bb the chart below still shoves about 40% of hands from the small blind, so this is not a tight range: shove-or-fold is a simple fallback that a full strategy with min-raises and limps beats by a little, not a low-variance default.