Long-term scenario
How Much Can $100 a Month Grow in 30 Years?
This scenario is where compound interest starts to look dramatic. The monthly amount is modest, but the long time horizon gives returns years to stack on top of prior returns.
Why this example matters
Over 30 years, you would contribute $36,000. At a 7% annual return with monthly compounding, the ending balance can exceed $120,000. That gap is the reason long-term investors care so much about starting early.
| Annual return | Total contributed | Approx. ending balance | Approx. growth above contributions |
|---|---|---|---|
| 5% | $36,000 | About $83,000 | About $47,000 |
| 7% | $36,000 | About $122,000 | About $86,000 |
| 10% | $36,000 | About $226,000 | About $190,000 |
What to notice
- The extra 20 years versus a 10-year plan are far more powerful than most beginners expect.
- Consistency is doing nearly as much work as the rate itself.
- Inflation still matters, so nominal growth is not the same as real purchasing power.