Guides
Short, clear guides to the money math behind our calculators.
- How to Calculate Overtime PayFederal overtime rules, the formula and worked examples.
- How to Convert an Hourly Wage to a Yearly SalaryThe 2,080 hour rule and how time off changes the math.
- How to Calculate Sales TaxAdd tax to a price, work backward and avoid common mistakes.
- How Much to Tip in the USCommon tipping amounts and how to split a bill.
- How to Calculate Percentage ChangeIncrease, decrease and the difference between percent and percentage points.
- How to Calculate Trip Gas CostEstimate fuel cost for a road trip and find your real mpg.