Free Online Percentage Calculator
Utilsly's Percentage Calculator is a free, all-in-one tool that handles every type of percentage calculation. With 8 calculator modes, you can solve any percentage problem instantly — from basic percent calculations to markup, margin, percent error, and ratio conversions.
What is a Percentage?
A percentage is a number or ratio expressed as a fraction of 100. The word "percent" comes from the Latin "per centum" meaning "by the hundred." Percentages are used everywhere — from discounts and taxes to growth rates and profit margins.
8 Percentage Calculators Explained
1. Basic Percentage — What is X% of Y?
The most common percentage calculation. Formula: Result = (Percentage / 100) × Value
2. What Percent — X is What % of Y?
Find what percentage one number is of another. Formula: Percentage = (Part / Whole) × 100
3. Percent Change — Increase and Decrease
Calculate percentage increase or decrease between two values. Formula: Change = ((New − Old) / |Old|) × 100
4. Reverse Percentage — Find the Original Value
Work backwards from a result to find the original number. Formula: Original = (Result / Percentage) × 100
5. Percent Difference
Find the symmetrical percentage difference between two values. Formula: Difference = (|A − B| / Average) × 100
6. Percent Error
Calculate accuracy of an experimental value vs theoretical. Formula: Error = (|Exp − Theo| / |Theo|) × 100
7. Markup and Profit Margin
Calculate markup (based on cost) and margin (based on selling price) for business pricing.
8. Ratio to Percent
Convert any ratio A:B to a percentage. Formula: Percentage = (A / B) × 100
Common Percentage Formulas
- X% of Y = (X / 100) × Y
- X is what % of Y = (X / Y) × 100
- % increase = ((New − Old) / Old) × 100
- % decrease = ((Old − New) / Old) × 100
- Original value = (Result / Percentage) × 100
- Markup % = (Profit / Cost) × 100
- Margin % = (Profit / Revenue) × 100
Is My Data Safe?
Yes. All calculations happen entirely in your browser. Nothing is sent to our servers.