3-phosphoglyceraldehyde or PGAL is 3-carbon glyceraldehyde 3-phosphate.

The PGA produced by this first step of the light independent reaction is converted to PGAL by using the energy in ATP and the reducing power of NADPH. This returns ADP, Pi, and NADP+ to the light reactions for their continued functioning.

PGAL can then be converted to glucose. RUBP is regenerated for the cycle to continue.

Balance sheet

6 CO2 + 6 RUBP (+ energy from 12 ATP and 12 NADPH) ----- 12 PGAL (3-carbon)

10 PGAL (+ energy from 6 ATP) ----- 6 RUBP (ie starting material regenerated)

2 PGAL ----- glucose (6-carbon).