Blog

Step-by-step guides, formulas, and worked examples from the Quick Calculators team.

• 

  401(k) vs Roth IRA: How to Pick the Right Retirement Account

  401(k) vs Roth IRA comes down to when you pay tax. Compare 2026 contribution limits, income rules, withdrawals, and a funding order to choose the right account.

• 

  How to Calculate a Tip (15%, 18%, 20%)

  Calculate a tip by multiplying the bill by the tip rate as a decimal. Quick methods for 15%, 18%, and 20%, splitting the tip, and worked examples.

• 

  How to Calculate a Percentage of a Number

  Calculate a percentage of a number by converting the percent to a decimal and multiplying. Formula, worked examples, and the reverse and percentage-change methods.