Compound Interest & Retirement

Most compound interest calculators answer one question about one pot of money. Compound answers the one people actually have: our household holds several accounts, they are taxed differently, and we want to know what they are worth — and whether they last once we are spending them. A PERSON, NOT A POT Put a folder around someone and their accounts add up. A Roth IRA, a pre-tax 401(k), a brokerage account, a 529 — Compound knows those dollars are not worth the same. It reports the balance and what is left after the tax that has not been collected yet. THE WHOLE HOUSEHOLD A folder for each person, and summary cards that add up the folders you choose — the two of you, the kids, everyone. Keep a summary at the top, move it to the bottom, or hide its amounts. PRIVATE WHEN YOU SHOW SOMEONE Mark any folder, account or summary private and its numbers show as dots until you open it. Hand your phone across the table without handing over your balances. WILL IT LAST? Every other calculator stops at the balance, which is where the question starts. Compound spends the accounts down in the order that costs the least tax and solves for what you could take each year and still finish at zero — with real federal brackets, your state's tax, required minimum distributions from 73 or 75, and Social Security from the year you claim it. AND IF THE MARKET MISBEHAVES? A steady 7% is a useful fiction. Compound runs your plan through every stretch of market history since 1928 — real S&P 500 returns, real Treasury returns, real inflation — and reports a count rather than a probability: how many of those retirements survived, and which ones broke. Then it compares four ways of taking the money out, and shows what a Roth conversion in the low-income years would cost now against later. PAY IN FOR A WHILE, THEN LET IT RIDE Contribute until a child turns 18 and let it compound until they retire — one scenario, not two. The chart marks the year the deposits stop. Touch and slide to read any year, from 30 to 100 years out. WHAT ELSE IT DOES • Employer match with a cap, and what the match alone is worth • A warning when a contribution is over the IRS limit • Fee drag in dollars, not a percentage nobody can feel • Compare people or accounts on one chart • Goal seek, milestones, Coast FIRE, and today's-money view • Trump accounts for children, taxed the way the law says • Year-by-year schedule, CSV export, share a plan, and a backup file you own FREE, WITH ONE PURCHASE FOR THE REST Compound is free: unlimited accounts and scenarios, the charts, goal seek, Compare, sharing, backup, privacy, and one folder with its after-tax total. No time limit, no ads. Compound Pro is a one-time $4.99 purchase that adds a folder for everyone else, summary cards, and the retirement tools — Will it last?, the history stress test, withdrawal strategies and Roth conversions. It is not a subscription. Family Sharing covers up to five family members, and nothing you have already made is ever locked. BUILT TO BE HONEST Every figure the app leans on is named: market history from Aswath Damodaran at NYU Stern, inflation from the Minneapolis Fed, brackets and RMD divisors from the IRS, state rates from the Tax Foundation. It lists what it does not model rather than guessing. YOUR NUMBERS STAY ON YOUR PHONE No account. No bank linking. No analytics, advertising or tracking. Everything you enter is held on your device and never sent anywhere. Compound is a calculator, not financial advice. It is not investment, tax or legal advice. Projections assume a constant return unless you run the historical test; real investments rise and fall, and past performance does not indicate future results. Talk to a qualified professional before acting on anything here.