Why don’t the potential savings for the next 30 days match the projection for the next 12 months?

As seen below, the projected savings for the next 30 days do not appear to be mathematically in line with the 12 month projection.
This is because in addition to looking at your currently uncovered workloads, Zesty’s algorithm also assesses any commitments (both Reserved Instances and Savings Plans) which are already in place and due to expire in the coming year.
The 12 month projection factors in 3 year RIs being purchased to replace all expiring commitments. This means you can expect to see a month-on-month increase in savings as your existing Reserved Instances or Savings Plans are replaced.