Percentage Calculator
Calculate percentages.
About the Percentage Calculator
Calculate percentages.
Percentage in Everyday Life
"Percent" comes from the Latin per centum, meaning "by the hundred." It's one of the most useful math concepts for daily life, yet one of the most commonly confused. Whether you're calculating a tip, figuring out a discount, or analyzing statistics, percentages are everywhere.
Common Calculations
- Percent Change: ((New Value - Old Value) / Old Value) × 100. Critical for tracking investment growth or weight loss.
- Percentage Difference: Used when comparing two values where neither is the "start" point, like comparing the height of two buildings.
- Reverse Percentage: Finding the original price before a tax or discount was applied.
Tips for Mental Math
Calculate percentages in your head instantly:
- 10%: Move the decimal one spot to the left. (10% of 50 is 5.0)
- 5%: Find 10%, then cut it in half.
- 20%: Find 10%, then double it.
- 15% (Standard Tip): Find 10%, add half of that amount. (10% of $40 is $4. Half is $2. Total tip is $6).