Compound interest, after tax.
Most calculators answer one question about one pot of money. Compound plans the whole household: every account each person holds, what it's really worth once the tax is paid, and whether it lasts when you start spending it.
Free to download · Pro is $4.99, once · no subscription · no ads
Compounded monthly, deposits at month end, before tax and inflation. The app adds the tax, the fees, the inflation — and the rest of your accounts.
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 child's 529. Compound knows those dollars aren't worth the same, so it reports the balance and what's left after the tax that hasn't been collected yet.
Folders for everyone
One folder per person, each with its own accounts, tax rates and retirement plan. Drag accounts between people; drag folders into the order you want.
After tax, not just on paper
Pre-tax, Roth, taxable, HSA and 529 money each treated as what it is — including the new Trump accounts for children. Set the rates once per person.
Summary cards
Totals for the folders you choose — the two of you, the kids, everyone. Keep them at the top, move them to the bottom, or hide the amounts.
Private when you show someone
Mark any folder, account or summary private and its numbers show as dots on the list until you open it. Handing your phone across the table stops being awkward.
A chart you can read
Touch and slide to read any year: the balance, what you'd put in by then, and on Compare every line at once. Thirty years to a hundred.
Pay in for part of it
Contribute until a child turns 18, then let it compound to retirement. The chart marks the year deposits stop.
Employer match, capped
The match most calculators leave out — with the annual cap — and what the match alone is worth at the end.
Limits and fees, in dollars
A warning when a contribution is over the IRS limit for that account type, and the fee you typed reported in dollars you can feel.
Goal seek and milestones
Solve for the contribution, the time or the return you need. See when you cross each milestone — and your Coast FIRE number — in today's money.
Made to be looked at every week.
Every calculator stops at the balance. This one keeps going.
The balance is where the real question starts. Compound spends a folder down in the order that costs the least tax — taxable first, pre-tax next, tax-free last — and tells you whether the money survives, and the most you could take each year and still finish at zero.
Will it last?
Spending that grows with inflation, a separate return for retirement, real 2026 federal brackets and your state's tax, required minimum distributions from 73 or 75 under SECURE 2.0, and Social Security or a pension with the year it starts.
History stress test
One steady return is a fiction. Your plan is replayed through every stretch of real market history since 1928 — actual stocks, bonds and inflation — and you get a count, not a probability: how many of those retirements survived, and which didn't.
Four ways to take it out
A fixed amount raised with inflation, guardrails, a percentage of the balance, and a floor and ceiling — side by side, so you can see which runs out first.
Roth conversions
How much more income fits before the next bracket, year by year, what filling it costs now, and what the same money would cost later. The arithmetic — never a recommendation.
Market and Treasury returns: Aswath Damodaran, NYU Stern. Inflation: CPI series from the Federal Reserve Bank of Minneapolis. Tax brackets: IRS 2026 inflation adjustments. RMD divisors: IRS Uniform Lifetime Table.
Your balances never leave your phone.
There's no account to make and no server to send anything to. Everything you type is stored on your device, and backups are a file you keep yourself. We couldn't see your numbers if we wanted to.
Read the privacy policy — it's short, and it says exactly that.
Free to use. One purchase for the rest.
- Unlimited accounts and scenarios
- One folder, with its after-tax total
- Charts from 30 to 100 years, year-by-year table
- Goal seek, milestones, today's-money view
- Compare on one chart
- Private folders and accounts
- Share a plan, backup and restore
- Everything in Compound
- A folder for every person in the household
- Summary cards across the folders you choose
- Will it last? — retirement drawdown
- History stress test since 1928
- Four withdrawal strategies compared
- Roth conversion planner
One in-app purchase, yours for good. Family Sharing covers up to five family members at no extra cost. No subscription, no ads, and nothing you've already made is ever locked.
Before you download.
Is it really free?
Yes. The calculator, the charts, Compare, sharing, backup and one folder with its after-tax total are free with no time limit and no ads. Compound Pro is a single $4.99 purchase for more folders, summary cards and the retirement tools.
Is Pro a subscription?
No. You pay once and it's yours. There's no renewal and nothing to cancel. Restore it on a new phone from Settings with the same Apple ID.
Does my family need to buy it separately?
No. With Family Sharing turned on, Compound Pro is shared with up to five other members of your family group.
Does it connect to my bank or brokerage?
No, on purpose. You type your balances and contributions in. Nothing is linked, synced or uploaded, so there's no login to protect and no data to leak.
What does it not model?
It says so in the app, on one page. Among other things: Medicare premiums and IRMAA, the net investment income tax, the taxation of Social Security benefits, and the Joint Life RMD table.
Which devices?
iPhone and iPad running iOS 17 or later.
Compound is a calculator, not financial advice. It shows what the arithmetic implies for the assumptions you enter. It isn't investment, tax or legal advice, and past market returns don't predict future ones. Talk to a qualified professional before acting on anything you see. Full disclaimer.