Learning center

Understand every number in your savings plan

Ten practical guides, from first principles to model limitations. Each one connects the formula to a scenario you can reproduce in the calculator.

Simple vs. compound interest: formulas, examples, and trade-offs

Learn how simple and compound interest differ, compare both on one scenario, and see why reinvesting changes the outcome.

See how monthly crediting affects ending capital and why an annual rate cannot simply be multiplied by time.

Compare taking interest as cash with reinvesting it, using the same assumptions and a transparent calculation model.

Understand how monthly deposits interact with compounding, timing, and realistic planning assumptions.

Understand quoted annual rates, effective annual yield, compounding frequency, and like-for-like comparisons.

Learn why a growing balance may still lose purchasing power and how to estimate real returns without false precision.

Model recurring fees, transaction costs, and jurisdiction-specific taxes to avoid overstating expected results.

Use the Rule of 72 as a quick estimate, understand its error range, and compare it with monthly compounding.

Build three scenarios instead of one forecast and test how rates, costs, and missed contributions affect the plan.

Set up a scenario, understand the order of calculations, read every output, and recognize what the model cannot predict.