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Finance guides
Every FinlyCalc calculator answers a "how much" question. These guides answer the "why" and "which" behind them, in plain English, with the same formulas the tools use and a worked example you can follow. No jargon, no signup, no advice you did not ask for.
Updated for 2026All guides
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How much house can I afford?
The 28/36 rule and what actually caps your budget
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15 vs 30 year mortgage
The monthly cost, the interest, and who each one suits
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What is PMI and how to remove it
Why it is charged, what it costs, and how to drop it
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How much for a down payment?
The real number, and the monthly plan to reach it
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How compound interest works
Interest on interest, the rule of 72, and why time wins
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Pay off a car loan faster
Small extra payments, real interest saved
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Should I refinance?
The break even test that answers it
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How big an emergency fund?
Three to six months, and how to size it
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How much to retire?
The 25x rule and the 4 percent rule explained
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APR vs interest rate
Why the two numbers differ, and which to compare
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Avalanche vs snowball
Least interest vs most motivation
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The 28/36 rule explained
The two ratios lenders use to size your loan
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Biweekly mortgage payments
One extra payment a year, years off the loan