Finance Calculators
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Compound Interest
$500/mo at 7% = $500K in 25 years
Dividend Income
$300K at 4% yield = $1,000/mo passive
Inflation Impact
$100K today = $55K purchasing power in 20 years
Take-Home Pay
$100K in Texas vs California = $9K/year difference
Loan Calculator
$300K mortgage at 7% = $1,996/mo for 30 years
ROI Calculator
Calculate return on investment with annualized rates
The numbers that matter
Most people don't know how much they actually take home after taxes. Or how much their savings will be worth in 20 years. These aren't complicated calculations — but they change how you think about money.
Why compound interest calculators exist
The S&P 500 has returned ~10% annually since 1926. After inflation, that's ~7%. Here's what that means:
| Monthly investment | After 10 years | After 25 years | After 40 years |
|---|---|---|---|
| $200/mo | $34,617 | $162,037 | $525,688 |
| $500/mo | $86,543 | $405,093 | $1,314,222 |
| $1,000/mo | $173,085 | $810,187 | $2,628,444 |
At 7% annual return. These are projections, not guarantees.
State taxes: $100K salary comparison
| State | State tax | Annual take-home | Monthly |
|---|---|---|---|
| Texas | 0% | $75,929 | $6,327 |
| Colorado | 4.4% | $71,529 | $5,961 |
| New York | 6.85% | $69,079 | $5,757 |
| California | 9.3% | $66,629 | $5,552 |
Texas vs California: $775/month difference. That's $9,300/year.
Inflation math
The Fed targets 2% inflation. Historically it's averaged 3%. At 3% inflation:
- $100K today → $74K purchasing power in 10 years
- $100K today → $55K purchasing power in 20 years
- $100K today → $41K purchasing power in 30 years
This is why savings accounts paying 0.5% are losing money in real terms.
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