See how your money grows over time. Your data stays in your browser.
| Year | Contributed | Interest | Balance |
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Compound interest means you earn interest on your interest. If you invest $1,000 at 7% annually, after one year you have $1,070. In year two, you earn 7% on $1,070 — not just the original $1,000. That extra $4.90 seems small, but over decades the effect is dramatic. After 30 years, that $1,000 becomes $7,612 without adding a single dollar.
Monthly contributions amplify this. Adding $500/month at 7% for 20 years gives you $260,464 — but you only contributed $125,000. More than half your final balance is interest that earned more interest.
Starting 10 years earlier matters more than doubling your contribution. Someone who invests $300/month from age 25 to 65 at 7% ends up with $745,000. Someone who invests $600/month from age 35 to 65 ends up with $567,000 — investing twice as much per month but ending with less, because they missed 10 years of compounding.
If you're already tracking your budget with Currents' budget calculator, look at your savings rate. Even a small increase redirected to investments makes a massive difference over time. Use the saving strategies guide to find money to invest.
A = P(1 + r/n)^(nt) + PMT × [((1 + r/n)^(nt) − 1) / (r/n)], where P = principal, r = annual rate, n = compounds per year, t = years, PMT = periodic contribution. This calculator handles all the math — just enter your numbers above.