Barbell Builder lets you edit the number of each plate in your gym and lets you modify, delete, and create custom plates. If you buy "Plate Editing", those changes will be saved between launches of the app. Otherwise all such changes will be lost when you exit the app. You can experiment with editing plates and using them in barbells to see if you think it's worth the price. If you buy the "Plate Editing" feature before you leave the app, your changes will be saved.
Many weight lifting programs have the lifter warm up by doing lighter sets of the exercise they're working on before they attempt their heavy work sets. In a linear progression, each set is heavier than the one before by the same amount.
Standard Full Size Olympic plates are 450 mm (about 17.7 inches). A bar with these plates on it is the right height off of the floor to do a regulation deadlift. A Bumper plate is a full size plate that is made of or coated with rubber. This allows it to be safely dropped to a weight lifting platform. Bumper plates are commonly used for Olympic lifts (like the Snatch or Clean and Jerk).
If you select Full Size plates, Barbell Builder will make sure all of the barbells in your sets include Full Size plates, along with whatever smaller plates are needed to make the target weight. If you select Bumper plates, Barbell Builder will make sure all barbells include Bumper plates and won't use any Full Size plates that are not Bumper plates, since you don't want hard metal to hit the ground if the bar is dropped.
It's not always mathematically possible to make a particular weight with a given set of plates. Barbell Builder will round up to the next largest weight that it can make.
Choosing Full Size or Bumper plates will force Barbell Builder to include plates of that type in every barbell, which will often mean that the first set must be heavier than its calculated target.
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