Nested if formula very long

[nplano1]

I have a nested if formula that is extremely long any ideas on how I can shorten it and still have it function properly?
because I have to do this 576 times

=IF(AG443=$AI$3,$AJ$3,IF(AG443=$AI$4,$AJ$4,IF(AG443=$AI$5,$AJ$5,IF(AG443=$AI$6,$AJ$6,IF(AG443=$AI$7,$AJ$7,IF(AG443=$AI$8,$AJ$8,IF(AG443=$AI$9,$AJ$9,IF(AG443=$AI$10,$AJ$10,IF(AG443=$AI$11,$AJ$11,IF(AG443=$AI$12,$AJ$12,IF(AG443=$AI$13,$AJ$13,IF(AG443=$AI$14,$AJ$14,IF(AG443=$AI$15,$AJ$15,IF(AG443=$AI$16,$AJ$16,IF(AG443=$AI$17,$AJ$17,IF(AG443=$AI$18,$AJ$18,IF(AG443=$AI$19,$AJ$19,IF(AG443=$AI$20,$AJ$20,IF(AG443=$AI$21,$AJ$21,IF(AG443=$AI$22,AJ$22,IF(AG443=0,"")))))))))))))))))))))

 

[sheetspread]

Use a lookup table

 

[njimack]

=if(ag443=0,"",index($aj$3:$aj$22,match(ag443,$ai$3:$ai$22,0)))

 

[gaz_chops]

Or

=if(AG443=0,"",vlookup(AG443,$AI$3:$AJ$22,2,0))

 

[nplano1]

Thank you that worked great, I have just started to learn about Index and match and this is perfect.
Thanks agan