Calculators
Compound Interest Calculator
Enter what you have, what you add each month, and how long you plan to leave it alone. The calculator shows the projected balance next to the two figures that give it meaning: how much of it you contributed, and how much of it was growth. Everything runs inside your browser. Your figures are never sent to Merieva or to anyone else, nothing is stored, and no account is required.
Results
Final balance
$120,965
Total contributed
$37,000
Total growth
$83,965
Total contributed is your starting amount plus every deposit you make. Total growth is the balance minus that figure. Over 30 years at 7% with annual compounding.
Year by year
Balances are shown at the end of each year. Scroll for later years.
| Year | Contributed to date | Balance |
|---|---|---|
| 1 | $2,200 | $2,270 |
| 2 | $3,400 | $3,629 |
| 3 | $4,600 | $5,083 |
| 4 | $5,800 | $6,639 |
| 5 | $7,000 | $8,303 |
| 6 | $8,200 | $10,085 |
| 7 | $9,400 | $11,991 |
| 8 | $10,600 | $14,030 |
| 9 | $11,800 | $16,212 |
| 10 | $13,000 | $18,547 |
| 11 | $14,200 | $21,045 |
| 12 | $15,400 | $23,718 |
| 13 | $16,600 | $26,579 |
| 14 | $17,800 | $29,639 |
| 15 | $19,000 | $32,914 |
| 16 | $20,200 | $36,418 |
| 17 | $21,400 | $40,167 |
| 18 | $22,600 | $44,179 |
| 19 | $23,800 | $48,471 |
| 20 | $25,000 | $53,064 |
| 21 | $26,200 | $57,979 |
| 22 | $27,400 | $63,237 |
| 23 | $28,600 | $68,864 |
| 24 | $29,800 | $74,884 |
| 25 | $31,000 | $81,326 |
| 26 | $32,200 | $88,219 |
| 27 | $33,400 | $95,594 |
| 28 | $34,600 | $103,486 |
| 29 | $35,800 | $111,930 |
| 30 | $37,000 | $120,965 |
If you would like more material like this, our free tools cover the same ground in more depth. No sign-up is needed to use this calculator.
How to read this number
The US stock market has returned roughly 10% a year over the long run in nominal terms. That figure is quoted so often it has started to sound like a promise. It is not. Inflation has averaged around 3% a year over the same stretch, which leaves a real return closer to 6.9% once you account for what a dollar actually buys. The two numbers answer different questions. The nominal number tells you what the account statement will say. The real number tells you what that money will be worth at the grocery store. If you are projecting decades ahead and want a figure you can plan a life around, the real return is the more useful one.
Compounding frequency matters more than most people expect, and it is the quiet reason two calculators can disagree about the same inputs. Ten percent compounded once a year is ten percent. Ten percent compounded monthly is an effective 10.47% a year, because each month’s interest starts earning interest of its own. Over thirty years that gap becomes substantial. Many calculators default to monthly compounding without saying so, which is part of why they return a larger number than you might expect. This one lets you choose, and tells you which assumption is in play.
None of this predicts the future. Past performance describes what happened to investors who lived through a particular set of decades; it is not a forecast, and real returns arrive unevenly rather than as a smooth annual average. A projection like this one is a way of understanding how contributions and time interact, not a statement about what your account will hold in thirty years.