Basis: Investing Calculators

Basis is a set of investing calculators and plain-English lessons for anyone making decisions about money, whether you already invest or are still working out how it all fits together.

Everything runs on your phone. No account, no ads, no tracking, and not a single network request.

52 CALCULATORS

From compound interest and dollar-cost averaging to Black-Scholes and bond duration, across eight categories: fundamentals and growth, stocks, ETFs and funds, options, futures and leverage, fixed income, risk and portfolio, and planning and life. 23 are free forever, at least two in every category.

Each one shows its formula, explains what the answer means, and links to the concept behind it.

70 LESSONS, IN PLAIN LANGUAGE

Seven learning paths that build in order: First steps, Shares and what you keep, Understanding ETFs, Options from zero, Futures and leverage, Fixed income without pain, and Risk and portfolio.

Every article follows the same five-block shape: the intuition, the formula, a worked example, when it applies, and the mistake it exists to prevent. That last block is the point. Each article ends with a short quiz, and the app remembers what you have read.

Every lesson and every glossary term is free. All 234 of them.

A DECISION JOURNAL

Write down why you made a decision, before you know how it turned out. Set a reminder for a month, three months, six months or a year, and read it back when the reminder arrives. Comparing what you thought would happen against what did is the fastest way to learn from your own decisions.

OPTIONS, EXPLAINED HONESTLY

14 strategies with profit-and-loss diagrams and editable legs. Every one carries a plain risk statement: the short straddle says outright that it is the position that ends accounts. This is a teaching tool, not a trading tool.

PORTFOLIO SIMULATOR

See how a mix of assets behaves across decades of returns rather than a single year, and drag along an efficient frontier to see what changing the mix costs and buys.

BILINGUAL

Complete in English and Spanish: all 52 calculators, all 70 lessons, all 234 glossary terms. Not a partial translation.

PRIVATE BY DESIGN

Your numbers never leave your device, because there is nowhere for them to go. The app makes no network requests at all. No account to create, nothing to sign in to, no analytics, no advertising.

BASIS PRO

One payment, forever. No subscription, nothing that renews, nothing to cancel. Pro unlocks the remaining 29 calculators, all 14 options strategies, the full portfolio simulator and efficient frontier, unlimited saved calculations and journal entries, and CSV and PDF export.

The free version is a real app, not a demo: 23 calculators, every lesson, every glossary term, and three saves of each kind.

Important: Basis is an educational and calculation tool. It does not provide investment advice or recommendations, and it shows no live market data. All results are estimates based on the values you type in. Investing carries risk, including loss of principal. Consult a licensed financial professional before making investment decisions.