1gallon = 231 in3, 1 inch = 2.54 cm)

1 gallon = 231 in
 1 inch = 2.54 cm

Honestly, I would say it will fill up because if your solving for the amount of centimeters in a gallon then the gallon would fill up. It just makes sense to me, don't know if it's correct because what I did was take the amount of centimeters in a inch and multiply it by the total amount of inches in a gallon.

HOPE THIS HELPS! ^_^