Investing & FIRE calculators
Every CoinGarden calculator in one place — free, no signup, and built to show how your money could grow. They run in order of difficulty, so start at the top and work down as each idea builds on the last. Educational only; not financial advice.
Compound Interest Calculator
See how an initial investment plus regular contributions can grow over time with compound interest — and how much of the final balance is growth versus your own money.
Open calculator → BeginnerHow Much to Invest Monthly to Reach Your Goal
Work out the monthly investment needed to reach a savings target — like $1 million by age 65 — from your current savings and an expected rate of return.
Open calculator → BeginnerWhen Will I Reach My Money Goal?
Enter a savings goal, what you have now, and how much you invest each month to see how many years it takes to get there — the timeline behind becoming a millionaire, hitting six figures, or any target.
Open calculator → IntermediateETF Fee Drag Calculator
Compare two funds' expense ratios and see how much a higher annual fee quietly costs you over decades — the money that leaves your account instead of compounding.
Open calculator → IntermediateDollar-Cost Averaging vs Lump Sum Calculator
Have a windfall to invest? Compare putting it all in at once against spreading it over several months — see which ends up ahead, by how much, and which one you'll actually stick with.
Open calculator → Intermediate401(k) Employer Match Calculator
See how much free money your employer's 401(k) match adds each year, whether you're leaving any on the table, and what that match alone could grow into by retirement.
Open calculator → AdvancedCoast FIRE Calculator
Find out how much you need invested today so you can stop contributing and still hit your retirement number — the point where compounding coasts you to financial independence.
Open calculator → IntermediateHow Much Do I Need to Live Off Dividends?
Work out the portfolio you'd need to live off dividend income at a given yield — and, in reverse, how much income the money you already have could pay. Honest about yield traps, taxes, and what dividends can't promise.
Open calculator → Beginner50/30/20 Budget Calculator
A calm monthly budget calculator built on the 50/30/20 rule — 50% needs, 30% wants, 20% savings. See where your money actually goes, get a warm read on your savings rate, and no judgement. Your numbers never leave your browser.
Open calculator → BeginnerDebt Payoff Calculator
See how long it takes to pay off a credit card or loan, and how much interest it costs, given your balance, APR, and monthly payment — plus how much sooner a bigger payment clears it. Educational, not financial advice.
Open calculator → BeginnerKakeibo Calculator — the Japanese Household Ledger
A calm kakeibo calculator built on the Japanese household practice from 1904. Set your intention, record spending by hand in four categories, and close the month by asking how you'd improve. Your numbers stay in your browser.
Open calculator → BeginnerThe Month Ahead — Cash Flow Calendar
Walk your balance forward one day at a time and see the days it dips below zero, before you live them. Five numbers, no bank login, nothing stored.
Open calculator → BeginnerPay Before or Pay After? Layaway vs Buy Now, Pay Later
The same instalments in the opposite order. Compare saving up, layaway and buy-now-pay-later side by side — including the honest part, which is that paid on time BNPL costs nothing extra.
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