Calculator Wizard
Percentage Guides
Clear, worked-example explanations of how percentages actually work in everyday situations — pay raises, tipping, grades, interest, and more.
How to Calculate a Pay Raise Percentage
The full formula for calculating a raise percentage, working backwards from a target percentage to a salary, and what counts as a competitive raise.
Read the guide →Tip vs. Sales Tax: How the Percentages Differ
They both look like a percentage added to your bill, but tax and tips work completely differently. Here's the real breakdown, with a worked restaurant example.
Read the guide →How to Calculate Your GPA Using Percentages
How percentage grades convert to GPA points, and a full worked example calculating a weighted GPA across classes with different credit hours.
Read the guide →Understanding Compound Interest
The compound interest formula explained step by step, compared directly against simple interest, plus the Rule of 72 shortcut.
Read the guide →APR vs. Interest Rate: What's the Difference?
Two percentages on every loan quote that look similar but measure different things — here's the real breakdown, with a worked mortgage example.
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