The net gain of ATP from the glycolysis of one molecule of glucose is

Explanation

Four ATP are made by substrate level phosphorylation but two were invested earlier to phosphorylate glucose and fructose 6 phosphate, so the net yield is two. Four is the tempting figure because it is the gross production and is quoted in the same paragraph of most textbooks. The larger numbers belong to the complete aerobic oxidation of glucose, not to glycolysis alone.