Compound Interest Calculator 2026: Long-Term Wealth Growth
Quick Answer
Compound interest: exponential growth over time. $500/month × 30 years at 7% = $844,359. Earlier you start = exponentially more wealth. Double contributions = double wealth. Rate matters: 7% vs. 3% = 3x more wealth.
Time Impact
| Start Age | Monthly | End at 65 | Total Return |
|---|---|---|---|
| 25 | $500 | $844k | $644k |
| 35 | $500 | $345k | $195k |
| 45 | $500 | $120k | $20k |
| 55 | $500 | $29k | -$31k |
Start 10 years earlier = 2.4x more wealth.
Rate of Return Impact
$500/month × 30 years:
| Return | End Amount |
|---|---|
| 0% | $180k |
| 3% | $270k |
| 5% | $444k |
| 7% | $844k |
| 10% | $1.98M |
7% vs. 3% = 3.1x more wealth.
Real-World Examples
- Retirement: $500/month age 25-65 at 7% = $844k
- Home down payment: $1k/month × 10 years at 5% = $135k
- Child education: $200/month × 18 years at 6% (529) = $65k
Inflation Adjustment
At 3% inflation: $844k future ≈ $397k in today's dollars. Still powerful. Use 4-5% real (after-inflation) returns for conservative planning.