Use conservative, mid, and optimistic return assumptions to see a realistic range of outcomes — then decide what’s feasible for your budget.
Open the Money Growth Calculator| Return rate | Final balance | Total contributed |
|---|---|---|
| 5% (conservative) | ~$361,000 | $156,000 |
| 7% (mid) | ~$529,000 | $156,000 |
| 10% (optimistic) | ~$980,000 | $156,000 |
Investing $100 a week for 30 years means contributing $156,000 of your own money — yet at a 7% return, compounding adds a remarkable $373,000 on top, growing your balance to around $529,000. Thirty years is where $100 a week becomes genuinely life-changing — at 10% returns you're approaching a million dollars from a habit that costs less than many people spend on coffee and lunches. For someone starting at 35, this could mean retiring at 65 with half a million dollars built entirely from a modest weekly contribution.
If you invest $100/week for 30 years, the result depends heavily on the return rate. Use the calculator to test a conservative, mid, and optimistic scenario.
It’s a solid starting habit. The best amount is one you can maintain consistently, then increase over time.
Use 5% for a conservative baseline, 7% for a mid-range estimate, and 10% as an optimistic scenario.
No. Treat results as estimates. You can lower your assumed return rate to be more conservative.
For long-term modelling, converting to monthly is usually close enough.
See the simple explanation on /how-compound-interest-works.html.
Keep exploring — these pages connect directly to calculators so you can run your own numbers.