Project savings growth with regular contributions, any compounding frequency, and a year-by-year breakdown. Free, runs in your browser.
First time here? Enter your starting amount and monthly contribution Your input is processed locally and disappears when you close the tab.
The point of a compound interest calculator is not the final number — it is seeing how much of that number you did not put in yourself. This free calculator projects savings growth with regular contributions and shows the split explicitly, year by year.\n\nThe calculation steps month by month rather than using the textbook annuity formula. That formula is only correct when contributions and compounding happen at the same frequency, which is often untrue in practice: people save monthly into accounts that compound quarterly or annually. Stepping handles any combination correctly, and a toggle covers contributing at the start of the month rather than the end, which earns roughly one extra month of growth per year.\n\nA year-by-year table shows the balance, what you added, and what the interest added, so the crossover point — where growth starts outpacing contributions — is visible rather than implied. That crossover is the actual argument for starting early, and it is much more persuasive as a number than as advice.\n\nOne honest caveat: this is a projection at a fixed rate, not a prediction. Real returns vary, and inflation, tax, and fees are all excluded, each of which matters over long periods. Everything runs in your browser. Pair it with the Loan EMI Calculator for borrowing rather than saving, or the Percentage Calculator for quick one-off sums.
Enter your starting amount and monthly contribution
Set the annual rate and number of years
Choose how often interest compounds
Read the projection and the year-by-year table
Interest is 59% of the final balance.
| Year | Added | Interest | Balance | |
|---|---|---|---|---|
| 1 | $13,000 | $821 | $13,821 | |
| 2 | $3,000 | $1,097 | $17,918 | |
| 3 | $3,000 | $1,393 | $22,312 | |
| 4 | $3,000 | $1,711 | $27,023 | |
| 5 | $3,000 | $2,052 | $32,074 | |
| 6 | $3,000 | $2,417 | $37,491 | |
| 7 | $3,000 | $2,808 | $43,300 | |
| 8 | $3,000 | $3,228 | $49,528 | |
| 9 | $3,000 | $3,679 | $56,206 | |
| 10 | $3,000 | $4,161 | $63,368 | |
| 11 | $3,000 | $4,679 | $71,047 | |
| 12 | $3,000 | $5,234 | $79,281 | |
| 13 | $3,000 | $5,829 | $88,110 | |
| 14 | $3,000 | $6,468 | $97,578 | |
| 15 | $3,000 | $7,152 | $107,730 | |
| 16 | $3,000 | $7,886 | $118,616 | |
| 17 | $3,000 | $8,673 | $130,289 | |
| 18 | $3,000 | $9,517 | $142,806 | |
| 19 | $3,000 | $10,422 | $156,227 | |
| 20 | $3,000 | $11,392 | $170,619 |
A projection at a fixed rate, not a prediction. Real returns vary year to year, and this ignores inflation, tax, and fees — all three of which matter over decades.
Contributing at the start of each month rather than the end earns roughly one extra month of growth per year — small annually, meaningful over decades.