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Compound Interest Calculator

Calculate investment growth with optional monthly contributions and year-by-year breakdown

Como usar Calculadora de Juros Compostos

  1. 1

    Enter your starting principal

    Type the initial lump-sum amount you are investing or have already saved.

  2. 2

    Set the annual interest rate

    Enter the expected annual return or interest rate as a percentage.

  3. 3

    Set the investment period

    Enter the number of years you plan to let the money grow.

  4. 4

    Choose a compounding frequency

    Select daily, monthly, quarterly, or annually to match how your account compounds interest.

  5. 5

    Optionally add monthly contributions

    Enter a regular monthly deposit to see how ongoing savings accelerate growth.

Perguntas frequentes

Is my data safe?
Yes. All processing happens entirely in your browser. Your data never leaves your device and is never uploaded to any server.
What is the compound interest formula?
For a lump sum: A = P × (1 + r/n)^(n×t), where P is principal, r is annual rate, n is compounding frequency per year, and t is years. For regular contributions an additional future-value-of-annuity term is added: PMT × ((1 + r/n)^(n×t) − 1) / (r/n), where PMT is the per-period contribution.
Which compounding frequency should I use?
Use the frequency that matches your actual account. Most savings accounts compound daily or monthly; many investment accounts and bonds use annual or quarterly compounding. Check your account agreement or ask your provider if you are unsure.
How are monthly contributions handled in the calculation?
Monthly contributions are annualized to match the selected compounding period and added using the future value of an annuity formula. This correctly accounts for contributions that themselves earn compound interest over the remaining time.
Does this calculator account for taxes?
No. The calculator shows pre-tax growth. In taxable accounts, interest and investment gains are typically subject to income or capital gains taxes each year, which would reduce the actual balance. Tax-advantaged accounts like 401(k)s and IRAs defer or eliminate this tax drag.

Saiba mais

O que é Compound Interest Calculator?

Calculate how your savings or investments grow over time with compound interest. Supports daily, monthly, quarterly, and annual compounding, plus optional regular monthly contributions to model realistic savings plans. See a year-by-year breakdown of your balance alongside a visual growth chart showing the split between contributions and earned interest. Everything runs entirely in your browser — no account required.

Por que usar Compound Interest Calculator?

  • Multiple compounding frequencies — choose daily, monthly, quarterly, or annual compounding to match your actual account.
  • Monthly contributions — add regular deposits to model realistic savings or investment accounts, not just lump-sum growth.
  • Year-by-year table — see exactly how your balance grows each year, including the split between what you contributed and what interest earned.
  • Visual growth chart — a stacked bar chart shows how interest increasingly dominates contributions over time.
  • 100% private — no data is ever sent to a server; all calculations run locally in your browser.

Casos de uso de Compound Interest Calculator

Retirement savings projection

Model how much your 401(k) or IRA could be worth at retirement by entering your current balance, expected return, years until retirement, and monthly contribution.

Savings account projection

See how a high-yield savings account grows with regular deposits, and compare the impact of different interest rates.

Investment comparison

Compare investment scenarios side by side — for example, investing $500/month for 30 years at 6% versus 8% — to understand the impact of return differences.

Education fund planning

Determine how much you need to save monthly to reach a college fund target within a specific number of years.

Dicas e boas práticas

  • 💡The Rule of 72 — divide 72 by your annual interest rate to estimate how many years it takes to double your money (e.g., at 6% your money doubles in roughly 12 years).
  • 💡Compounding frequency matters less than you might think — the difference between daily and monthly compounding is usually less than 0.1% annually; what matters most is the interest rate itself.
  • 💡Inflation erodes real returns — a 7% nominal return with 3% inflation yields only about 4% in real purchasing power, so consider whether your target rate accounts for inflation.
  • 💡Regular contributions compound too — even small monthly additions benefit from compounding, which is why starting early and contributing consistently is more powerful than timing the market.

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