Guides
Practical guides for finance, health, tax, and time calculations. Page 3 of 6.
How to Calculate Your Monthly Car Payment (Formula + Examples)
Learn the exact formula to calculate your monthly car payment, with step-by-step examples for different rates, loan terms, and down payments — plus a free calculator.
Tax & BusinessHow Do Federal Income Tax Brackets Work? (With Examples)
Federal income tax brackets are marginal — only income above each threshold is taxed at the higher rate. See how brackets work with step-by-step examples.
HealthWhat Is a Healthy BMI? How to Calculate and Interpret It
Calculate adult BMI, understand precise category boundaries, and distinguish a screening result from a diagnosis or personal weight target.
Time & DateHow Many Days Between Two Dates? (With Formula & Examples)
Calculate the exact number of days between two dates — the formula, step-by-step examples, calendar days vs business days, and a free date difference calculator.
FinanceWhat Is the 4% Rule for Retirement? Does It Still Work?
The 4% rule says withdraw 4% of your portfolio each year in retirement. Here's where it came from, how to calculate your savings target, and whether it still holds up.
Tax & BusinessHow to Calculate Payroll Taxes Step by Step
Learn how to calculate payroll taxes: Social Security, Medicare, federal withholding, and FUTA — with step-by-step examples for employees and employers.
FinanceHow to Compare Two Loan Offers and Pick the Better Deal
Compare fixed-rate loan payments and interest, distinguish contractual rates from APR, and account for fees separately from the calculator.
FinanceHow Much Should You Tip at a Restaurant? (2025 Guide)
The standard restaurant tip is 15–20%, but the right amount depends on service, establishment type, and whether you're dining in or ordering delivery. Here's the full breakdown.
FinanceWhat Is a Good Debt-to-Income Ratio? (DTI Explained)
Your debt-to-income ratio tells lenders if you can handle more debt. Learn what counts as a good DTI, how to calculate yours, and what to do if it's too high.