I've found 6 lbs of syrup fits in a half-gallon jar. About the same for honey and simple syrup. "Half again" is about as close as you'll get.
Remember one unassailable statistic, as explained by the late, great George Carlin: "Just think of how stupid the average person is, and then realize half of them are even stupider!"
"I would like to die on Mars, just not on impact." Elon Musk