Pocket money growth calculator
See how weekly savings grow — week by week, month by month — with clear numbers and a simple chart.
Calculator personalLogic updated April 2026
This calculator shows how much money you can save up week by week if you put a portion of your pocket money aside each week. It also shows how a savings account can help your money grow a tiny bit on its own, just for sitting there. Saving small amounts every week really does add up — even if it doesn't feel like it at first.
How this is calculated
Formula
Each week: balance += (allowance × savings% / 100) ; balance × (1 + annualGrowth/100/52)Step-by-step
- Multiply your weekly allowance by the savings percentage to find how much you save each week
- Add that weekly saving to your balance at the start of every week
- If your savings account pays interest, multiply the balance by a tiny weekly growth factor at the end of each week
- Repeat for as many weeks as you want to see (the calculator caps at 5 years so the chart stays useful)
- The final number tells you how much you'd have if you stuck with it
- Track total saved (just the contributions) and total growth (the interest that grew on its own)
- Rounding mode
- ROUND_HALF_UP
- Precision
- 20-digit internal precision (Decimal.js), rounded to 2 decimal places for display
- Logic last reviewed
Assumptions & limitations
What this calculator assumes
- Money is saved at the start of each week
- Growth is added each week at the annual rate divided by 52
- Growth is applied to the balance after each weekly contribution
- Projection is capped at 260 weeks (5 years)
- The same allowance and savings percent apply every week
What this calculator doesn’t account for
- Real savings accounts may have minimum balances or different rate rules
- Doesn't model spending some of your savings later
- Doesn't account for one-off bonuses (birthdays, holidays, helping with extra chores)
- Doesn't include any account fees
- Real life has weeks where you save more or less — this uses a flat weekly amount
Worked example
A child gets $20 a week in pocket money, saves half of it every week into an account that pays 3% a year, and tracks the balance for 2 years.
| Input | Value |
|---|---|
| Weekly allowance | $20 |
| Savings percent | 50% |
| Annual growth | 3% |
| Weeks | 104 (2 years) |
Total saved: $1,040 — Growth earned: ~$33 — Final balance: ~$1,073
$20 × 50% = $10 saved each week. Over 104 weeks that's $1,040 just from saving. The 3% per year on a slowly growing balance adds about $33 of free money on top. So your balance would be a bit over $1,000 after 2 years — enough for something significant. Doubling the savings percent to 100% would make the balance ~$2,000+, showing how the savings rate is the biggest lever.
Frequently asked questions
How does saving pocket money add up?
Every week you add a small amount, and over time those small amounts get really big. Saving just $5 a week is $260 a year — enough for a nice gift or a chunk of a bigger goal. The trick is doing it every week without skipping. Even saving $1 or $2 a week is worth doing, because the habit matters more than the amount when you're starting.
Why does saving early matter?
Two reasons: you build the habit, which sticks with you for life, and your money has more time to grow. Money saved when you're 10 has 8 years to earn interest before you might want it for something at 18 — that's much more growth than money saved at 17. Saving early gives time a chance to do the work for you.
What if I save a little more each week?
The calculator shows the answer instantly — try changing the savings percent and see how the final number jumps. Saving 60% instead of 50% over 2 years gives you about $200 more. Going from 50% to 75% gives you about $500 more. The lever that grows your balance fastest is how much you save each week, not the interest rate.
How long until I reach my goal?
Use the kids saving goal calculator alongside this one — that one tells you how many weeks until you hit a specific target. If you want $200 for something special and you save $10 a week, that's 20 weeks (about 5 months). The two calculators answer different sides of the same question: this one shows what your habit produces; the goal calculator works backwards from a target.
What's the best place to keep my pocket money savings?
A savings account designed for kids — most banks have one. Look for one with no fees and a reasonable interest rate. Keeping money in a piggy bank is fine for very small amounts, but once you have $50 or more, an account adds up faster because the bank pays you a tiny bit for keeping your money there. Ask a parent or carer for help opening one if you don't have an account yet.
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