A lot of kits reckon 50pg ish from a fat Hela cell. A recent kit I read reckons more like 10pg. However, I have found a few papers working back to 1pg. We have just extracted from a known amount of Hela cells and using a Nagel kit and got 15pg or 25pg with a Zymo kit. However a more uncommon cell line was only 4pg. Thought it would be interesting to pull together a few other peoples' experiences, since it's not always that easy to find in the literature.