How Much Will My Child Have Saved by 18?
Enter what you're putting away each week and see what it reaches by their eighteenth birthday — plus what the same amount would have reached if you had started earlier or later.
What $10/week reaches by 18, by starting age
Same weekly amount, same 4% rate, starting from nothing — only the start age changes. The table updates as you change the inputs above.
| Start age | Years saving | You contribute | Balance at 18 |
|---|---|---|---|
| 4 | 14 | $7,280 | $9,754 |
| 5 | 13 | $6,760 | $8,862 |
| 6 | 12 | $6,240 | $8,005 |
| 7 | 11 | $5,720 | $7,182 |
| 8 | 10 | $5,200 | $6,391 |
| 9 | 9 | $4,680 | $5,631 |
| 10 | 8 | $4,160 | $4,900 |
| 11 | 7 | $3,640 | $4,199 |
| 12 | 6 | $3,120 | $3,525 |
| 13 | 5 | $2,600 | $2,877 |
| 14 | 4 | $2,080 | $2,255 |
| 15 | 3 | $1,560 | $1,657 |
| 16 | 2 | $1,040 | $1,082 |
| 17 | 1 | $520 | $530 |
Why the early rows are so much larger
The gap between starting at 6 and starting at 12 is far wider than the six years of extra contributions would suggest. The early deposits have the longest time to compound, so each one contributes more than a later deposit of the same size. Money added at 17 barely compounds at all — it is essentially just saved.
That is also why the "cost of waiting one more year" figure above is usually larger than a year of deposits. You lose the contributions and the growth they would have produced.
What rate should you use?
For a real savings account, use whatever your bank actually pays. For a family bank where you pay the interest yourself, the rate is whatever you decide — see the compound interest calculator for what different rates cost you, and how to run a bank of mom and dad for how to set one up.
Set the rate to 0 to see contributions alone. The difference between that and your real rate is exactly what the interest is doing for you.
Track it without a spreadsheet
Bank of Dad keeps a running balance for each child, applies interest automatically on the schedule you set, and logs every deposit and withdrawal. Free, no card, no monthly fee.
Frequently asked questions
How much should I save for my child each week?
There is no correct amount — it depends entirely on what your family can sustain. Consistency matters far more than size: $5 a week from age 6 reaches more by 18 than $15 a week started at 14, because the early deposits compound for twelve years instead of four.
Is it too late to start saving for my teenager?
No, but the maths changes. With four years left, interest contributes relatively little and the balance is close to what you put in. Set the rate to 0 in the calculator to see that directly. Saving still works; it just behaves like saving rather than like compounding.
Does this account for inflation?
No. Every figure is in today's dollars at face value, so a balance shown for eighteen years from now will buy less then than the same number would buy today. Treat the output as a nominal balance, not as purchasing power.