Compound Interest Calculator

Free interest calculator for daily, monthly, quarterly and annual compounding, with regular deposits.

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More calculators

Daily Compound Interest Calculator

Interest compounded every day, with optional monthly deposits.

Monthly Compound Interest Calculator

Interest compounded every month, with optional monthly deposits.

Daily to Annual Interest Rate Calculator

Turn a daily rate into APR and APY, or an annual rate into daily and monthly.

APR to APY Calculator

Convert APR to APY and back for any compounding frequency.

CD Calculator

What a certificate of deposit is worth at maturity.

High-Yield Savings Calculator

Savings and money market growth with monthly deposits.

Interest on 10,000 Dollars

What $10,000 earns per year, month and day, and what it grows to in 10 and 20 years.

Interest on 100,000 Dollars

What $100,000 earns per month and year, and how long to reach $1 million.

Interest on 500,000 Dollars

What $500,000 earns per year, month and day, and the FDIC $250,000 limit.

Interest on 1 Million Dollars

What $1 million earns per year, month and day at common rates.

Interest on 2 Million Dollars

What $2 million earns per year, month and day, and FDIC limits.

Compound Interest with Withdrawals

How long savings last when you withdraw every month.

Stock Return Calculator

Stock profit, total return with dividends and annualized return.

Growth Rate Calculator

Year-over-year growth and CAGR between two values.

How much interest does a balance earn in a year?

First-year interest = balance × annual yield (APY). The monthly figure is roughly one-twelfth of that. The table uses example rates, not current bank rates.

Balance3%3.5%4%4.5%5%
$10,000$300$350$400$450$500
$100,000$3,000$3,500$4,000$4,500$5,000
$1,000,000$30,000$35,000$40,000$45,000$50,000
$2,000,000$60,000$70,000$80,000$90,000$100,000

For example, $2 million at 5% APY earns about $100,000 in the first year, or roughly $8,333 a month. After the first year the interest itself starts earning interest, so each later year earns a little more. The pages for $10,000, $100,000, $500,000, $1 million and $2 million break this down per month and per day.

Compound interest table: what $10,000 grows to

Compounded annually with no further deposits. Each cell is A = 10,000 × (1 + r)t.

Rate5 years10 years20 years30 years
3%$11,592.74$13,439.16$18,061.11$24,272.62
5%$12,762.82$16,288.95$26,532.98$43,219.42
7%$14,025.52$19,671.51$38,696.84$76,122.55
10%$16,105.10$25,937.42$67,275.00$174,494.02

Worked example: $10,000 at 5% compounded monthly for 10 years

  1. Monthly rate: 5% ÷ 12 = 0.4167%.
  2. Number of compounding periods: 12 × 10 = 120.
  3. Growth factor: (1 + 0.05/12)120 ≈ 1.6470.
  4. Final balance: $10,000 × 1.6470 = $16,470.09, of which $6,470.09 is interest.

With $100 added at the end of every month, the same example ends at $31,998.32: $22,000.00 of your own money and $9,998.32 of interest.

The same money compounded daily ends at $16,486.65, only a few dollars more. See the monthly and daily compound interest calculators to add regular deposits.

Does compounding frequency matter?

The same $10,000 at 5% for 10 years under each frequency:

CompoundingPeriods per yearBalance after 10 years
Annually1$16,288.95
Semiannually2$16,386.16
Quarterly4$16,436.19
Monthly12$16,470.09
Daily365$16,486.65

More frequent compounding pays slightly more because interest joins the balance sooner, but the difference shrinks quickly: daily beats monthly by only $16.55 here. The rate and the time matter far more.

If you only have a daily interest rate, for example 0.0137% a day (or 0.04% a day, which is 14.6% a year as APR and about 15.7% as APY), the daily to annual interest rate calculator converts it to the annual rate (APR) and the effective annual yield (APY) first, which you can then enter above. To compare a quoted APR with an APY, use the APR to APY calculator.

Simple vs compound interest

Simple interest is paid only on the original amount; compound interest is also paid on the interest already earned. On $10,000 at 7% for 20 years:

FormulaBalance after 20 yearsInterest
Simple interestP × (1 + r × t)$24,000.00$14,000.00
Compound interest (annual)P × (1 + r)t$38,696.84$28,696.84

The gap, $14,696.84, is interest earned on interest, and it widens the longer the money stays invested.

How long does it take to double your money? The rule of 72

Divide 72 by the annual rate to estimate the years needed to double: about 14 years at 5%, 10 years at 7.2% and 7 years at 10%. The exact figure is ln 2 ÷ ln(1 + r); at 7% that is 10.2 years against the rule's 10.3. To find the rate between two values, use the growth rate (CAGR) calculator.

Compound Interest Calculator - Frequently Asked Questions

The more you learn, the more you earn.

There are different ways to calculate compound interest depending on your needs. Our compound interest calculator uses advanced financial formulas to account for both the growth of the initial principal and the impact of regular contributions.

The Complete Formula:

Compound Interest Formula: FV = P × (1 + r/n)^nt + PMT × ((1 + r/n)^nt - 1) / (r/n)

Key Variables:

  • FV: Future Value (final amount)
  • P: Principal (initial deposit)
  • r: Annual interest rate (as decimal)
  • n: Compounding frequency per year (daily=365, monthly=12, etc.)
  • t: Time period in years
  • PMT: Regular payment/contribution amount per period

The calculator accounts for different compounding frequencies and regular contributions, so you can compare scenarios on the same inputs.

Daily (n=365)

Interest calculated 365 times/year. Common for high-yield savings accounts.

Monthly (n=12)

Interest calculated 12 times/year. Standard for savings & CDs.

Annual (n=1)

Interest calculated once/year. Common for bonds.

More frequent compounding generally results in higher returns because interest is added to your principal more often.

  1. Enter Initial Deposit (P): Start with the amount you're investing.
  2. Choose Frequency (n): Select daily, monthly, quarterly, or annually.
  3. Set Interest Rate (r): Enter the annual rate (e.g., 5%).
  4. Specify Time (t): How long will your money grow?
  5. Add Contributions: Optional regular deposits.

Quick Example:

$10,000 at 5% annual interest, compounded monthly for 10 years, with $100 added at the end of each month = $31,998.32 total value ($22,000 deposited, $9,998.32 interest earned).

Results use the standard formula A = P(1 + r/n)^(nt) plus the future value of a series for regular contributions. Rates are nominal annual rates and regular contributions are added at the end of each period, unless you choose otherwise.

  • $10,000 at 5%, compounded monthly for 10 years, $100 added each month: $31,998.32.
  • $10,000 at 6%, compounded monthly for 10 years, $200 added each month: $50,969.84.
  • $10,000 at 5%, compounded monthly for 10 years, no deposits: $16,470.09.

You can reproduce each of these with the inputs above. Last reviewed November 2026.

  • $10,000 start, $500 added monthly, 7%, 30 years? About $691,150.47 (monthly compounding, deposits at month end).
  • How much to invest monthly to reach $1,000,000 in 20 years at 7%? About $1,919.66 a month from zero; use the Goal-Based tab to solve it with your own starting balance.
  • $500,000 and $3,000 withdrawn monthly at 6%, how long will it last? Just under 30 years on this site's assumptions; see the calculator with withdrawals.
  • Daily vs monthly compounding on $10,000 at 5% for 10 years? Annual $16,288.95, monthly $16,470.09, daily $16,486.65.
  • Can I add deposits and withdrawals? Deposits are in the main calculator; withdrawals have their own page because they change the answer from growth to depletion time.

Rates are nominal annual rates. Last reviewed November 2026.

A compound interest calculator is a financial tool that helps you calculate how your money grows over time when interest is added to your principal and then earns interest itself. Unlike simple interest calculators that only calculate interest on the principal, a compound interest calculator accounts for the exponential growth that occurs when interest compounds.

Our compound interest calculator supports multiple compounding frequencies:

  • Daily compounding: Interest calculated 365 times per year
  • Monthly compounding: Interest calculated 12 times per year
  • Quarterly compounding: Interest calculated 4 times per year
  • Semi-annual compounding: Interest calculated 2 times per year
  • Annual compounding: Interest calculated once per year

This makes it ideal for calculating investment growth, savings account returns, loan interest, and retirement planning scenarios.

Yes! Our compound interest calculator is 100% free with no registration, sign-up, or hidden fees required. You can calculate unlimited scenarios for your investments, savings, loans, or retirement planning without any cost.

We believe financial planning tools should be accessible to everyone, whether you're learning about compound interest or planning your own savings.

What you get for free:

  • Unlimited calculations with no restrictions
  • Support for all compounding frequencies
  • Regular contribution calculations
  • Detailed breakdown of results
  • No personal information required

The calculator applies the standard compound interest formula for the frequency you choose, including regular contributions. Real accounts can differ slightly: banks may round at each period, credit interest on different days, or change the rate over time. Use the results as a projection, not as a quote from your bank.

If you use an annual interest rate but select a monthly compounding frequency, the calculator will divide the annual rate by 12 to calculate the monthly rate. For example, an annual rate of 12% would be converted to a 1% monthly rate.

You can select the desired compounding frequency from the dropdown menu. The available frequencies are daily, monthly, quarterly, semiannually, and annually.