Compound Interest Calculator
See how your savings grow with compound interest and regular contributions.
このページはまだ完全に翻訳されていません。一部は英語で表示されます。
Enter your principal, annual interest rate, number of years, optional periodic contribution, and choose how often interest compounds.
計算式と方法
FV = P(1 + r/n)^(nt) + C · (((1 + r/n)^(nt) − 1) / (r/n)), where P is principal, r the annual rate, n the compounds per year, t the years, and C the contribution per period.
Contributions are treated as an ordinary annuity (added at the end of each compounding period). All math runs locally in your browser.
計算例
- $1,000 at 5% for 10 years, compounded monthly, no contributions → ≈ $1,647.01 future value — 1000 × (1 + 0.05/12)^(12×10).
前提条件
- The interest rate stays constant for the whole period.
- Contributions occur at the end of each compounding period.
- Taxes, fees, and inflation are not deducted.
よくある間違い
- Confusing the nominal annual rate with the effective annual rate.
- Entering a monthly rate where an annual rate is expected.
よくある質問
What is compound interest?
Compound interest is interest calculated on both the initial principal and the accumulated interest from previous periods, so growth accelerates over time.
How does compounding frequency affect results?
More frequent compounding (e.g. monthly vs annually) slightly increases the future value because interest is added and re-invested more often.
プライバシー
すべての処理はブラウザ内でローカルに実行され、データがアップロードされることはありません。
免責事項: This tool provides estimates for educational purposes only and is not financial advice.
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