An independent reference, verified before it ships.

Why this site exists

The internet is not short of compound interest calculators. It is short of calculators that you can audit. Most major personal-finance sites compute a future value using methods they do not document and assumptions they do not surface — including, in several cases we tested, a hidden simple-interest fallback when the rate is below 1 %. The result is that two reputable sites can disagree by tens of thousands of dollars on the same inputs and neither will tell you why.

rifinance.xyz exists to remove that ambiguity for one specific calculation. The engine is open, the formula is on a separate page, the reference cases are listed, and the author who reviews the math is a real, named, regulated professional.

Editorial principles

• Three-method verification. Every figure passes the closed-form formula, a per-period simulation, and an Excel FV() cross-check. Disagreement greater than one cent blocks release.
• Named accountability. The reviewer is a CFP® in private practice. Her credentials are verifiable through the CFP Board's public directory.
• No commission relationships. rifinance.xyz does not promote, recommend, or accept compensation from any financial product, broker, advisor, or platform.
• No upselling. The calculator is free, will remain free, and contains no upsell to a paid version.
• Privacy by architecture. The calculator runs entirely in your browser. Inputs are not transmitted, logged, or stored.

The team

The site is operated as a one-person editorial project. Maggie Chen, CFP®, reviews every release of the calculator and every page of reference content before publication. She holds final editorial authority and is the named accountable person for every figure on the site.

A second technical reviewer — an independent JavaScript engineer based in Berlin — performs a code review on every release of the calculator engine, focusing on the per-period accumulation loop and the Intl.NumberFormat handling for non-USD currencies. The engineer is named in the public changelog only when their review has flagged a substantive issue.

How the calculator is verified

1. Reference cases. A fixed list of 24 input/output pairs covering edge cases (zero rate, zero contribution, one-year horizon, daily compounding over 50 years, beginning-of-period contributions). Every release runs against the list and must match to the cent.
2. Closed-form vs. simulation. For every reference case, the closed-form formula and the per-period loop must agree. Where they diverge, the loop wins and the formula is investigated.
3. Excel cross-check. The same inputs are fed to Excel's FV(rate, nper, pmt, pv, type). The two results are compared at full precision.
4. Currency rendering. All seven supported currencies are rendered through Intl.NumberFormat and visually inspected for thousand-separator and decimal-symbol correctness in EN-US locale.

What this site is not

• It is not investment advice. The calculator is a math tool. Whether to invest, in what, and at what rate of return is a decision to make with a human advisor.
• It is not tax-aware. The future value is pre-tax. Capital gains, dividend, and ordinary-income tax treatment can materially affect the realised result.
• It is not inflation-adjusted. The output is in nominal dollars. For real-terms purchasing power, run it through an inflation calculator separately.
• It is not a savings tracker. We do not store balances, link to accounts, or aggregate any data.

Get in touch

Editorial corrections, calculation disagreements, accessibility issues, and partnership enquiries are all handled through the contact page. If you have spotted a math error, please include the exact inputs and the result you expected — we triage every such report within one business day.