Compound interest estimates how money grows when earned interest is added to the balance and can earn interest again. This calculator separates the starting amount, recurring contributions, growth rate, compounding schedule, and time horizon so you can understand the result.
Use the result as a planning estimate rather than a promise. Real returns may vary because rates, fees, taxes, deposits, withdrawals, and market performance can change over time.
Compound interest is interest calculated on the original principal plus interest accumulated in earlier periods. Compared with simple interest, the repeated reinvestment of interest can make growth accelerate over longer periods.
The effective result depends on both the annual rate and how often interest is compounded. Monthly compounding does not automatically mean a higher annual return; the stated rate and the calculation convention must be interpreted together.
A = P × (1 + r/n)^(n×t)Convert the annual percentage to a decimal, divide the rate by the number of compounding periods, and raise the growth factor to the total number of periods. Subtracting P from A gives the estimated interest earned.
FV = P × (1 + r/n)^(n×t) + C × [((1 + r/n)^(n×t) − 1) / (r/n)]This version adds the future value of equal contributions made at the end of each compounding period. If contributions are made at the beginning of each period, the contribution portion is multiplied by one additional growth factor.
The zero-rate case is handled separately: future value equals the principal plus the total contributions. The calculator assumes a constant rate, regular timing, and no fees or taxes unless the tool provides fields for them.
How much will 1,000 grow to at 5% annual interest compounded once per year for 10 years?
The account gains 628.89 in estimated interest, so the balance is about 1,628.89 before fees or taxes.
What is the future value of 2,500 at 4.8% compounded monthly for 3 years?
Monthly compounding produces an estimated balance of 2,886.38, including 386.38 of growth.
How much can 200 grow when 100 is added at the end of every month for 2 years at 6%?
The estimated interest is 168.63; most of the final balance comes from the regular deposits.
What is the estimated value of 5,000 at 7% compounded annually for 20 years?
Time is the main driver in this example: the estimated interest is more than the original principal.
What is the balance when 750 is deposited and the stated annual rate is 0% for 5 years?
With a zero rate, the final balance is exactly the money deposited: 2,250, before any fees.
How does 3,000 at 6% for 5 years compare when compounded annually versus monthly?
At the same nominal rate, monthly compounding is about 31.87 higher in this example because interest is added more frequently.
Future value is the estimated ending balance. It includes the original principal and, when entered, the regular contributions plus estimated interest.
Estimated interest is the future value minus the money you put in. Keep these numbers separate so a high final balance is not mistaken for a high rate of return.
Entering 5 instead of 0.05 is correct only when the rate field expects a percentage. Do not convert the value twice.
Confusing nominal annual rate with effective annual yield can produce different results. Check the compounding frequency and the convention used by the account.
Ignoring contribution timing, fees, taxes, inflation, or withdrawals can make a projection look more certain than it is.
The estimate assumes a constant rate and regular compounding. It does not predict market returns or guarantee an investment outcome.
A negative rate, zero periods, invalid frequency, or mixed units may require special handling. The zero-rate case should not divide by the periodic rate.
For loans, deposits may represent payments rather than savings contributions, so confirm whether the calculator is designed for an investment, account, or debt schedule.
It is interest calculated on the principal and previously accumulated interest.
It is the number of times interest is added to the balance each year.
They are included when the contribution field is used; the result depends on their timing.
At the same nominal rate it can produce a slightly higher result than annual compounding, but the stated rate and fees matter.
The balance is the principal plus all contributions because no interest is earned.
No. It is a mathematical projection under stated assumptions, not a guarantee.
Fees reduce the balance or effective rate, so a fee-free estimate may be optimistic.
Only if the inputs and payment timing match the loan formula; many loan schedules need separate amortization calculations.
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