Eliminate Debt or Invest Calculator View Calculator See if it's better to pay down debt or invest your extra money until it can pay off the debt all at once. Will you pay more interest on your loan or earn more on your investment? Enter the information about your debt and investment and this calculator will show you how to lower debt the faster by showing what happens if you pay down debt first or put it into an investment until it grows to the pay off debt amount. Learn more about putting this calculator or other calculators on your website.