Compounding the ledger…
A compound interest calculator with the math showing. Investment growth, the year-by-year ledger, and an inflation toggle so the final number reads in today’s dollars.
Enter a starting balance, a monthly contribution, an expected return, and a horizon. Optionally toggle inflation to see the result in today’s purchasing power.
| Year | Contributions | Growth | Ending balance |
|---|---|---|---|
| 1 | $6,000.00 | $919.19 | $16,919.19 |
| 2 | $6,000.00 | $1,419.38 | $24,338.58 |
| 3 | $6,000.00 | $1,955.73 | $32,294.31 |
| 4 | $6,000.00 | $2,530.85 | $40,825.16 |
| 5 | $6,000.00 | $3,147.55 | $49,972.70 |
| 6 | $6,000.00 | $3,808.82 | $59,781.53 |
| 7 | $6,000.00 | $4,517.90 | $70,299.43 |
| 8 | $6,000.00 | $5,278.24 | $81,577.68 |
| 9 | $6,000.00 | $6,093.55 | $93,671.22 |
| 10 | $6,000.00 | $6,967.79 | $106,639.02 |
| 11 | $6,000.00 | $7,905.24 | $120,544.25 |
| 12 | $6,000.00 | $8,910.45 | $135,454.70 |
| 13 | $6,000.00 | $9,988.32 | $151,443.02 |
| 14 | $6,000.00 | $11,144.12 | $168,587.14 |
| 15 | $6,000.00 | $12,383.47 | $186,970.62 |
| 16 | $6,000.00 | $13,712.41 | $206,683.03 |
| 17 | $6,000.00 | $15,137.43 | $227,820.45 |
| 18 | $6,000.00 | $16,665.45 | $250,485.91 |
| 19 | $6,000.00 | $18,303.94 | $274,789.85 |
| 20 | $6,000.00 | $20,060.87 | $300,850.72 |
| 21 | $6,000.00 | $21,944.82 | $328,795.53 |
| 22 | $6,000.00 | $23,964.95 | $358,760.48 |
| 23 | $6,000.00 | $26,131.12 | $390,891.60 |
| 24 | $6,000.00 | $28,453.88 | $425,345.48 |
| 25 | $6,000.00 | $30,944.55 | $462,290.03 |
| 26 | $6,000.00 | $33,615.28 | $501,905.30 |
| 27 | $6,000.00 | $36,479.07 | $544,384.37 |
| 28 | $6,000.00 | $39,549.88 | $589,934.26 |
| 29 | $6,000.00 | $42,842.69 | $638,776.94 |
| 30 | $6,000.00 | $46,373.53 | $691,150.47 |
Most compound-interest calculators online hide the shape of the curve behind a single endpoint number, and almost none of them handle inflation with any honesty — you end up reading a $2.4M projection that feels real until you remember a cup of coffee will cost $12 by then. This one shows the trajectory (via the sparkline), the ledger (every year broken out), and the real purchasing power (when you ask for it), so the final number arrives with context instead of false precision. Monthly compounding is the default because it reflects how auto-investing actually happens after a paycheck. Nothing leaves your browser.