Free Financial Tool
Compound Interest Calculator
See how your money grows over time with the power of compound interest and regular contributions
Your Inputs
You Contribute
$145,000
Interest Earned
$147,729
Final Balance
$292,729
Growth Over Time
Year-by-Year Breakdown
| Year | Contributions | Interest | Balance |
|---|---|---|---|
| 0 | $25,000 | $0 | $25,000 |
| 1 | $31,000 | $1,564 | $32,564 |
| 2 | $37,000 | $3,554 | $40,554 |
| 3 | $43,000 | $5,995 | $48,995 |
| 4 | $49,000 | $8,913 | $57,913 |
| 5 | $55,000 | $12,333 | $67,333 |
| 6 | $61,000 | $16,285 | $77,285 |
| 7 | $67,000 | $20,798 | $87,798 |
| 8 | $73,000 | $25,904 | $98,904 |
| 9 | $79,000 | $31,636 | $110,636 |
| 10 | $85,000 | $38,031 | $123,031 |
| 11 | $91,000 | $45,124 | $136,124 |
| 12 | $97,000 | $52,956 | $149,956 |
| 13 | $103,000 | $61,569 | $164,569 |
| 14 | $109,000 | $71,005 | $180,005 |
| 15 | $115,000 | $81,312 | $196,312 |
| 16 | $121,000 | $92,540 | $213,540 |
| 17 | $127,000 | $104,738 | $231,738 |
| 18 | $133,000 | $117,964 | $250,964 |
| 19 | $139,000 | $132,274 | $271,274 |
| 20 | $145,000 | $147,729 | $292,729 |
Want a guaranteed rate?
Lock in today's best fixed annuity rates — guaranteed growth, tax-deferred, principal protected.
See Today's RatesHow Compound Interest Works
Compound interest is the process of earning interest on both your original deposit and the interest that deposit has already earned. Each compounding period, your balance grows — and the next period's interest is calculated on that larger balance. Over time, this creates exponential growth rather than the straight-line growth of simple interest.
The formula behind this calculator is A = P(1 + r/n)nt, where P is your starting principal, r is the annual interest rate, n is the compounding frequency, and t is the number of years. When you add regular contributions, the calculator layers in the future value of an annuity so you can see exactly how saving consistently accelerates growth.
Higher Rate
Every 1% increase in rate dramatically accelerates long-term growth.
More Time
The longer your money compounds, the steeper the growth curve becomes.
Regular Contributions
Adding even small amounts monthly supercharges compounding.
Compound Interest Examples
Real growth scenarios at a 5.5% guaranteed rate (compounded monthly) with no additional contributions.
$10,000 at 5.5% for 20 years
$29,962
Nearly triples with no additional contributions
$25,000 at 5.5% for 20 years
$74,905
Doubles twice over on principal alone
$50,000 at 5.5% for 30 years
$263,226
More than 5x your starting balance
Compounding Frequency Explained
Compounding frequency is how often interest is calculated and added to your balance. More frequent compounding means interest earns interest sooner. Here's how a $25,000 deposit at 5.5% grows over 20 years under different frequencies:
| Frequency | APY | Final Balance |
|---|---|---|
| Annually | 5.50% | $73,655 |
| Monthly | 5.64% | $74,905 |
| Daily | 5.65% | $74,968 |
The difference between monthly and daily compounding is small — under $100 over 20 years on a $25,000 deposit. The annual rate itself matters far more than the compounding frequency.
The Tax-Deferral Advantage
In a taxable savings account or CD, you pay taxes on interest every year — reducing the amount left to compound. A fixed annuity grows tax-deferred, so 100% of your earnings keep working until you withdraw. Over 20 years, tax deferral at a 5.5% rate can add tens of thousands of dollars compared to a taxable account in a similar bracket.
Combined with guaranteed rates up to 5.55% APY and full principal protection, fixed annuities are one of the most powerful compound-growth vehicles available to retirees and pre-retirees.
Compound Interest FAQ
What is compound interest?
Compound interest is interest earned on both your initial principal and the interest that has already accumulated. Unlike simple interest, which only pays on your original deposit, compound interest lets your earnings generate their own earnings — creating exponential growth over time. The more frequently interest compounds, the faster your balance grows.
How is compound interest calculated?
The compound interest formula is A = P(1 + r/n)^(nt), where A is the final amount, P is the principal, r is the annual interest rate (as a decimal), n is the number of times interest compounds per year, and t is the number of years. For regular contributions, add the future value of an annuity: PMT × [((1 + r/n)^(nt) − 1) / (r/n)], where PMT is the contribution per compounding period.
How often should interest compound?
More frequent compounding produces slightly more interest. Daily compounding yields more than monthly, which yields more than annual. However, the difference is modest at typical rates — the annual rate (APY) matters far more than compounding frequency. A 5.5% rate compounded monthly earns about 5.64% APY; the same rate compounded daily earns about 5.65% APY.
What is the difference between compound interest and simple interest?
Simple interest is calculated only on your original principal. Compound interest is calculated on your principal plus all accumulated interest. Over 20 years at 5.5%, a $25,000 deposit earns $27,500 in simple interest but $48,905 in compound interest — nearly double — because each year's interest earns its own interest in subsequent years.
How much will $25,000 grow in 20 years at 5.5%?
A $25,000 deposit earning 5.5% compounded monthly grows to approximately $74,905 after 20 years — nearly tripling your money with no additional contributions. Adding $500 per month brings the final balance to roughly $292,729, of which about $147,729 is interest earned on top of your $145,000 in total contributions.
Does compound interest work with monthly contributions?
Yes. When you add money regularly, each contribution begins compounding from the moment it is deposited. The earlier you start and the more consistently you contribute, the more dramatic the compounding effect. This calculator models monthly or yearly contributions on top of your starting principal.
What is a good compound interest rate for retirement savings?
Bank savings accounts and CDs typically compound at 3–4.5% (as of 2026). Fixed annuities (MYGAs) offer guaranteed rates up to 5.55% APY, compounded tax-deferred — meaning you keep more of the growth working for you instead of losing a portion to taxes each year. The higher the rate and the longer the term, the more powerful compounding becomes.
Is compound interest tax-deferred?
Interest in a standard savings account or CD is taxed each year, which reduces the amount available to compound. Fixed annuities grow tax-deferred — you pay no taxes on earnings until you withdraw, allowing the full balance to compound uninterrupted. This tax deferral can add a meaningful boost to long-term growth, especially in higher tax brackets.