Guides & Articles

Practical, plain-English guides to go with our calculators — 78 articles and counting.

• Financial Calculators

  Debt-to-Income Ratio Calculator Guide

  What actually counts as "debt" in a DTI calculation, why lenders gatekeep on this one number, and how front-end and back-end limits differ by loan type.

• Financial Calculators

  Mortgage Calculator Guide

  Understand what makes up your monthly mortgage payment (PITI and PMI) and how changing your down payment, rate, or term shifts the numbers.

• Financial Calculators

  Loan Calculator Guide

  Learn the difference between a loan's interest rate and its APR, and how loan term changes your total cost far more than most people expect.

• Financial Calculators

  Auto Loan Calculator Guide

  See how stretching an auto loan to a longer term lowers your payment but raises total interest and negative-equity risk.

• Financial Calculators

  Amortization Calculator Guide

  Learn to read each row of an amortization schedule and see exactly how one extra principal payment reshapes every row that follows.

• Financial Calculators

  Retirement Calculator Guide

  Learn the 4% rule and the "25x expenses" shortcut for estimating your retirement number, and which calculator inputs matter most.

• Financial Calculators

  Compound Interest Calculator Guide

  Understand compound interest with the Rule of 72 shortcut, and see why how often interest compounds changes your actual return.

• Financial Calculators

  Investment Calculator Guide

  See how starting early and contributing consistently affects long-term investment growth more than trying to pick the perfect entry point.

• Financial Calculators

  Income Tax Calculator Guide

  Learn why moving into a higher tax bracket doesn't raise tax on all your income, and the difference between marginal and effective tax rates.

• Financial Calculators

  Interest Calculator Guide

  Interest works the same way whether you owe it or collect it. Learn to read this calculator from both sides before picking a more specific tool.

• Financial Calculators

  Payment Calculator Guide

  Already know your loan amount, rate, and term? Skip the loan shopping and get straight to the monthly payment number with this worked example.

• Financial Calculators

  Currency Calculator Guide

  Why exchange rate swings matter more as the amount grows, and when locking in a rate or forward contract beats waiting.