MoneyBasisGuides
Learn the numbers behind the decision.
Practical explanations, worked examples, and tools to try with your own numbers.
Home & Mortgage
Home & Mortgage · 5 min read
How Mortgage Amortization Works
See how the same loan payment gradually shifts from interest to principal.
Read guide →$320,000 loan · 6.5% fixed · 30 years
- Year 1 interest
- $20,695
- Year 30 interest
- $833
Same scheduled payment. More principal repaid over time.
Home & Mortgage · 6 min read
Rent vs Buy: Compare Cash Costs, Equity and Opportunity Cost
Follow the same starting money and monthly resources down two housing paths.
Read guide →Two paths with equal starting resources
- Buy
- Equity + investments
- Rent
- Investment portfolio
Compare the full financial picture, beyond rent versus mortgage.
Saving & Investing
Saving & Investing · 5 min read
Compound Interest: Growth, Contributions and Inflation
Understand what you put in, what the model adds and what future dollars can buy.
Read guide →20 years · $10,000 + $500/month · 7% nominal, compounded monthly
- Contributed
- $130,000
- Modeled growth
- $170,851
- Future balance
- $300,851
Separate the money you add from the growth you assume.
Saving & Investing · 5 min read
How Much to Save Each Month for a Specific Goal
Start with the funding gap, then see how time and an assumed return change the deposit.
Read guide →$12,000 goal · $3,000 saved · no return assumed
- 12 months
- $750/mo
- 24 months
- $375/mo
- 36 months
- $250/mo
Same funding gap. More time means a smaller monthly deposit.
Saving & Investing · 5 min read
Nominal vs Real Return: What Future Dollars Can Buy
A larger dollar balance does not always mean more purchasing power.
Read guide →$10,000 over 10 years · 7% annual growth · 3% inflation
- Future dollars
- $19,672
- Today’s buying power
- $14,637
One future balance, viewed in two different dollar units.
Saving & Investing · 5 min read
APR vs APY vs Investment Return
Match the rate definition to the calculator field before entering a percentage.
Read guide →Illustrative rates · separate examples
- APR
- 6.5%
- APY
- 5.00%
- Investment return
- 7.00%
Same “%” symbol. Different meaning.
Retirement
Income & Budgeting
Income & Budgeting · 5 min read
Salary to Hourly: Gross Pay, Paid Weeks and Tax Estimates
Separate gross-pay arithmetic from an annual federal tax estimate.
Read guide →40 hours per week · 52 paid weeks
- Annual gross pay
- $62,400
- Hourly equivalent
- $30
A different pay period changes the unit, not the salary.
Income & Budgeting · 5 min read
Gross Pay vs Net Pay: Taxes, Benefits and Deductions
Understand why a tax deduction, a retirement transfer and take-home cash are different.
Read guide →2026 example · one single worker · federal tax and FICA only
- Annual gross pay
- $75,000
- Estimated net pay
- $61,593
Follow the deductions between what you earn and what you keep.
Income & Budgeting · 5 min read
How to Build a Monthly Budget
Give income, spending, savings transfers and unassigned cash distinct jobs.
Read guide →Monthly example with an explicit $500 savings transfer
- Income
- $5,000
- Expenses
- $3,700
- Unassigned cash
- $800
Account for bills and savings before deciding what is left.
Income & Budgeting · 4 min read
Savings Rate vs Remaining Cash Flow
A percentage is only meaningful when its numerator and income basis are named.
Read guide →Same $5,000 monthly take-home income
- Savings transfer
- $500
- Unassigned cash
- $800
Money left over is only savings when you set it aside.
Debt
Debt · 5 min read
Debt Snowball vs Debt Avalanche
Separate the order of extra payments from actual payoff dates and interest costs.
Read guide →Two ways to prioritize extra debt payments
- Snowball
- Smallest balance
- Avalanche
- Highest APR
Reserve the minimums, then choose where the extra payment goes.
Debt · 5 min read
Extra Loan Payments: How Principal, Interest and Payoff Change
Follow an extra payment through the balance, later interest and final payoff.
Read guide →$10,000 loan · 12% annual rate
- $300 per month
- 41 months
- $400 per month
- 29 months
Extra principal reduces the balance that future interest is charged on.