[coolman26]

My guess is grain crush, then measurements. When I first started I was in the 52% range on almost everything. It came back to crush and me not paying attention to measurements. My boil off wasn’t right. My deadspace was horrendous back then. Crush from my HB store was also terrible. The easiest correction is scale up on the next batch for your efficiency, then make corrections.

[ynotbrusum]

I suppose the word choice of "significant" was poor.  I meant to emphasize that overall, pH can have a significant impact, if it is way out of whack, which I assumed was not the case with someone using one of those recipe calculators....