Methodology · GL-SAVE-003
How the Savings Goal Calculator works
This page documents how the Savings Goal Calculator produces its figures: the engines and formulas it runs, the rule packs it reads statutory values from, the official documents those packs cite, and how the engines are verified.
Engines and formulas
- E14 · Savings engine
§13.11 future value with contributions, cross-checked by period simulation; goal solving by closed-form inversion verified through the forward calculation.
Registered formulas: §13.11 future value
- E24 · Financial solver
Monotonic bisection with §13.28 safeguards: bounds, tolerances, iteration caps, discontinuity detection and unattainable-target reporting.
Registered formulas: §13.28 bisection
Verification
Engines carry boundary tests at every bracket edge, property-based tests, reconciliation invariants and, where official worked examples exist, tests that reproduce them exactly. The full source register is on the sources page.