The Calvin cycle is the name of the chain of reactions that combine the CO_2 , water and sun light to form sugar molecules. The main reactant of Calvin cycle is CO_2 and the main product is glucose.
The reaction starts with the combination of CO_2 with RuBP and the catalyst of reaction is an organic molecule that is called RuBisCO enzyme. The product of reaction is un unstable 6 carbon molecule that splits into two molecules of phosphoglyceric acid (PGA).
The addition of of phosphate group from ATP and the addition of hydrogen from NADH + H^+ that breaks the phosphate bond down transform the 3PG molecules in phosphoglyceraldehyde molecules, C_3H_7O_6P.
The product of reaction is glucose C_6H_12O_2 that results from two molecules of 3PG.