Guides & Articles
Practical, plain-English guides to go with our calculators — 78 articles and counting.
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Financial Calculators
Inflation Calculator Guide
A 2% savings rate feels safe, but if inflation runs at 3%, your cash is losing ground. Learn the nominal vs. real return gap and what it costs you.
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Financial Calculators
Finance Calculator Guide
Learn the time-value-of-money logic behind present value, future value, payment, and rate — and how to pick which one to solve for.
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Financial Calculators
Mortgage Payoff Calculator Guide
Biweekly mortgage payments vs. a flat extra monthly amount: a side-by-side numbers comparison to see which payoff strategy actually saves more.
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Financial Calculators
Salary Calculator Guide
Why multiplying by 52 weeks or 2,080 hours overstates real pay, and how to convert hourly, weekly, and monthly wages correctly.
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Financial Calculators
401K Calculator Guide
Understand how employer 401(k) matching works, why not claiming the full match leaves free money on the table, and how contribution limits work.
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Financial Calculators
Interest Rate Calculator Guide
Only told the monthly payment? Back into the real interest rate on a dealer or retailer financing offer before you sign anything.
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Financial Calculators
Sales Tax Calculator Guide
See why sales tax differs by state, county, and even city block, plus how to back out the pre-tax price from any receipt total.
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Financial Calculators
House Affordability Calculator Guide
How lenders actually calculate front-end and back-end DTI ratios, why FHA and conventional limits differ, and which ratio decides your loan approval.
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Financial Calculators
Savings Calculator Guide
Why sizing an emergency fund works differently than saving for a vacation or a car, and how to set the right target for each in the savings calculator.
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Financial Calculators
Rent Calculator Guide
Why the 30% rent rule can overstate what you can afford once car payments and student loans are counted against your income.
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Financial Calculators
Marriage Tax Calculator Guide
See exactly when marriage helps your taxes and when it hurts: a real bonus example with unequal incomes and a real penalty example with two equal high earners.
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Financial Calculators
Estate Tax Calculator Guide
Federal estate tax rarely applies below eight figures, but state exemptions can start at $1 million. Here's how the two interact.