Calculator methodology
Understand the assumptions behind GoalAdvisor’s free financial tools.
What GoalAdvisor provides
GoalAdvisor is an independent financial-literacy project with free mathematical tools. It does not provide personalized financial plans, investment recommendations, account connections, or trading. The calculators use assumptions you choose and show their methods and limitations on each page.
How we check the models
Model checks compare results with independent month-by-month calculations, known examples, and boundary inputs. We also check page links and simulated interface events. These are engineering checks, not professional certification or a promise that a result is suitable for your circumstances. Current model review date: October 10, 2026.
Return and contribution conventions
Investment-growth and fee models use effective annual returns converted to equivalent periodic rates. Contributions arrive at period-end. Fees are approximated by subtracting an annual percentage from return. The savings-goal tool instead uses a nominal annual interest rate divided by 12. Debt assumes APR divided by 12. Different conventions can produce different answers.
What the models leave out
Constant-return illustrations omit market volatility and the order of investment returns. Retirement accumulation stops at retirement; a withdrawal-rate target does not test whether savings will last. Taxes are not calculated. Inflation is a user assumption, not live CPI. Dividend reinvestment is annual and simplified. Each calculator lists its additional limits.
Privacy and sharing
Calculator inputs are processed in your browser. The calculator code does not write them to an application database, local storage, or cookies. Shared scenario links contain inputs; recipients can read them. Hosting, browser history, and sign-in providers may retain other data. Read the privacy notice for the full distinction.
Explore the calculators
- Compound Interest Calculator
- Retirement Calculator
- Savings Goal Calculator
- Inflation Calculator
- Investment Fee Impact Calculator
- Debt Payoff Calculator
- Net Worth Calculator
- Asset Allocation Calculator
- Dividend Reinvestment Calculator
Download the calculator methods and example data for independent inspection. Results are educational illustrations. Read the financial disclosures and terms of use.
Questions or corrections
To report a possible error, email hello@goaladvisor.com. Include the calculator name and hypothetical inputs so the result can be reproduced; do not send identifying account information.