Interest on Interest
Simple interest grows linearly — 5% on $1,000 is $50/year, forever. Compound interest grows exponentially — you earn interest on your original amount and on the interest you've already earned. Over long periods, this difference is enormous.
The Real Numbers: Early vs. Late
The most powerful illustration of compounding is comparing two savers who contribute the same total amount but start at different times. Assume 7% average annual return (a reasonable long-term stock market estimate):
| Early Saver (Sara) | Late Saver (Mike) | |
|---|---|---|
| Starts saving at age | 25 | 35 |
| Annual contribution | $3,000 | $3,000 |
| Stops contributing at age | 35 (only 10 years) | 65 (30 years) |
| Total contributed | $30,000 | $90,000 |
| Balance at age 65 | ~$338,000 | ~$303,000 |
Sara contributed one-third as much money as Mike but ended up with more — because she started 10 years earlier and let compounding do the rest. Time is the most valuable ingredient.
What This Means for Your KC 401(k)
Every dollar KC deposits into your 401(k) — the 3% flat contribution, the employer match — has decades to compound if you're earlier in your career. That's why the KC match is often described as "free money": it's not just the match amount, it's 20–30 years of compounding on top of it.
Consider what happens to a $3,000 KC match deposited at age 30, assuming 7% annual return and no additional contributions to that specific money:
- At age 40: ~$5,900
- At age 50: ~$11,600
- At age 60: ~$22,800
- At age 67: ~$37,100
That one year's match becomes $37,000 by retirement — without you contributing another dollar. Multiply that across 30 years of KC matches and compounding, and the picture becomes clear.
Compounding Works Against You Too: Debt
The same force that grows your wealth in a 401(k) works against you in high-interest debt. A credit card at 22% APR compounds your balance just as relentlessly as a good investment compounds your savings — but in the wrong direction.
This is why financial advisors consistently prioritize paying off high-interest debt before increasing investment contributions beyond the employer match. A credit card at 22% guaranteed savings on interest outperforms most investments.
The One Action to Take Today
If you're not yet contributing to your KC 401(k), start — even at 1%. Then increase it until you hit 5% to capture the full KC match. The compound growth on that money, starting today, is more valuable than starting next year at a higher rate.