Compound interest calculator
What steady saving grows into, with deposits on any schedule, yearly raises and any compounding frequency. Work backward from a goal, see it in today's dollars, or upload your account history to measure the return you actually earned.
Quick answer: Saving $500 a month for 30 years at 7% compounded monthly, starting from nothing, grows to about $609,986, of which $180,000 is your deposits and $429,986 is interest.
By John Crane, MBA & the Editorial Team · Updated for the 2026 tax year. How we check our numbers
Balance after 25 years
$462,290.03
Worth $184,611 in today's dollars at 3.7% inflation
| Your deposits | $160,000 | 34.6% |
|---|---|---|
| Interest earned | $302,290 | 65.4% |
- Final balance
- $462,290
- Total deposited
- $160,000
- Interest earned
- $302,290
- In today's dollars
- $184,611
- Effective yield
- 7.229%
- Interest share
- 65.4%
Growth over time
Year by year
25 years| Year | Deposits | Interest | Balance | Today's dollars |
|---|---|---|---|---|
| 01 2027 | $6,000.00 | $919.19 | $16,919.19 | $16,309.23 |
| 02 2028 | $6,000.00 | $1,419.38 | $24,338.58 | $22,615.32 |
| 03 2029 | $6,000.00 | $1,955.73 | $32,294.31 | $28,925.92 |
| 04 2030 | $6,000.00 | $2,530.85 | $40,825.16 | $35,248.68 |
| 05 2031 | $6,000.00 | $3,147.55 | $49,972.70 | $41,591.22 |
| 06 2032 | $6,000.00 | $3,808.82 | $59,781.53 | $47,961.14 |
| 07 2033 | $6,000.00 | $4,517.90 | $70,299.43 | $54,366.09 |
| 08 2034 | $6,000.00 | $5,278.24 | $81,577.68 | $60,813.69 |
| 09 2035 | $6,000.00 | $6,093.55 | $93,671.22 | $67,311.61 |
| 10 2036 | $6,000.00 | $6,967.79 | $106,639.02 | $73,867.55 |
How this is calculated
Growth per deposit period
i = (1 + r / m)^(m / p) − 1
r is the annual rate, m the compounding periods per year and p the deposits per year. Each period the balance earns i, then the deposit is added (or added first, if deposits are at the start). Continuous compounding uses e^(r/p) − 1.
Today's dollars
Future balances are divided by (1 + inflation)^years, so the real line shows buying power at today's prices. The default inflation rate is the latest year-over-year CPI from the Bureau of Labor Statistics.
Your actual return
From your deposits and balances we compute the money-weighted annual return (the same XIRR method spreadsheets use), which accounts for when each dollar went in. The projection replays the same deposits at your assumed rate.
Sources
Related guides
- The Rule of 72: how fast money doublesDivide 72 by the rate to estimate how long money takes to double. How close the shortcut comes at every rate, and what it says about debt and inflation.
Questions
How often should interest compound?
More frequent compounding earns slightly more: 5% compounded daily is about a 5.13% effective yield versus 5% compounded yearly. For savings accounts compare APY, which already includes compounding.
How much do I need to save each month to reach a goal?
Choose Solve for Deposit, enter your target balance and timeline, and the calculator returns the exact deposit per period, including any yearly raises you plan.
Why does starting earlier matter so much?
Interest earns interest, so growth accelerates over time. Open Compare to see how waiting five years shrinks the final balance even with the same deposits.