حاسبة الفائدة المركّبة
Compound interest is the single most powerful concept in personal finance — Einstein supposedly called it "the eighth wonder of the world." The reason is that you earn interest not just on your original principal but on all the interest you have already earned, creating exponential growth over time. Our compound interest calculator shows you exactly how much a one-time deposit, a monthly contribution, or both will grow over any time horizon at any rate.
النمو سنة بسنة
| السنة | الرصيد | المساهمات | الفائدة المكتسبة |
|---|---|---|---|
الرصيد النهائي
The Rule of 72 — How Long to Double Your Money
The Rule of 72 is a simple mental math shortcut for estimating how long it takes to double an investment. Divide 72 by the annual interest rate, and you get the approximate number of years. At 6% annual return, it takes roughly 12 years to double (72 ÷ 6 = 12). At 9%, it's only 8 years.
This rule reveals why even small differences in interest rates compound dramatically over time. The difference between a 6% and a 9% return might seem small year-to-year, but over 30 years, the 9% portfolio can be more than double the size of the 6% portfolio.
The flip side is also true: debt compounds against you. Credit card debt at 24% APR doubles in just 3 years by this rule. High-interest debt should always be addressed before prioritizing investments, since the guaranteed return of paying off 24% debt beats nearly any investment.
كيف تعزز المساهمات الشهرية الفائدة المركّبة
The biggest lever most investors underestimate is consistent monthly contributions. While a large lump sum grows well, adding even a modest amount each month dramatically accelerates wealth accumulation because each new contribution immediately starts earning compound returns.
Consider the difference: $10,000 invested at 7% for 30 years grows to about $76,000. But if you add just $200/month, the final balance jumps to roughly $320,000 — more than 4 times higher, from contributions that total only $72,000. The interest earned on those contributions makes up the difference.
Starting early matters enormously. A person who invests $200/month for 30 years will typically end up with more than someone who invests $400/month for only 15 years, even though the second person contributed the same total amount. Time in the market beats timing the market.
حول Compound Interest Calculator
Compound interest is the single most powerful concept in personal finance — Einstein supposedly called it "the eighth wonder of the world." The reason is that you earn interest not just on your original principal but on all the interest you have already earned, creating exponential growth over time. Our compound interest calculator shows you exactly how much a one-time deposit, a monthly contribution, or both will grow over any time horizon at any rate.
كيفية الاستخدام
- Enter your starting principal (or zero if you are starting from scratch).
- Enter your monthly contribution. Even $100/month compounds dramatically over decades.
- Set the annual interest rate. Long-term S&P 500 average is ~10% nominal, ~7% real (inflation-adjusted).
- Set the time period in years. The longer, the more dramatic the curve.
- Choose compounding frequency. Monthly is the most common for investments; daily for high-yield savings.
الصيغة والمنهجية
Future value FV = 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.
حالات الاستخدام الشائعة
- Projecting retirement account balance at age 65
- Comparing a savings account vs index fund over 20 years
- Showing your kids why starting early matters
- Modeling debt payoff in reverse (compound interest against you)
- Setting realistic college savings targets
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