What is the chemical formula for glucose?

The chemical formula for glucose is C6H12O6. It shows that one glucose molecule contains six carbon atoms, twelve hydrogen atoms, and six oxygen atoms.

Glucose is a six-carbon monosaccharide, or simple sugar, and is one of the central energy molecules in biology. Plants produce glucose-related carbohydrates through photosynthesis, using carbon dioxide and water powered by light energy. Cells can then break glucose down through glycolysis and cellular respiration to make ATP, the immediately usable energy currency of the cell.

A frequent source of confusion is that several different compounds share the formula C6H12O6. Fructose and galactose, for example, have the same numbers of each element but different arrangements of atoms, making them structural or stereoisomeric relatives rather than glucose itself. Sucrose, table sugar, has the different formula C12H22O11 because it is made from glucose and fructose joined together.

The glucose formula also helps explain why photosynthesis is often summarized with the equation 6CO2 + 6H2O → C6H12O6 + 6O2, though the real process involves many intermediate reactions and does not produce free glucose in a single step.