Percentage Calculator
Calculate percentages instantly for discounts, tips, increases, decreases, and all common formulas with live results.
Understanding percentage calculations
Percentage calculators solve everyday math problems involving discounts, tips, sales increases, test scores, and financial planning. The basic formula—(Part ÷ Whole) × 100—calculates what portion one number represents of another. For example, if you score 45 out of 50 on a test, that's (45 ÷ 50) × 100 = 90%.
Common scenarios include calculating sale prices (subtract percentage mode), adding sales tax or tips (add percentage mode), finding percentage increases or decreases between values, and determining what percentage one value represents of another. This calculator handles all six standard percentage formulas with instant results that update as you type—all calculations run privately in your browser with no data sent to servers.
FAQs
How does this percentage calculator work?
Select a calculation mode (what percent, percent of, increase/decrease, etc.), enter your two values, and the calculator instantly computes the result using standard percentage formulas. All calculations run in your browser—no data is sent to servers.
What is the formula for calculating percentages?
The basic formula is (Part/Whole) × 100 = Percentage. For example, "What is 15% of 200?" uses (15/100) × 200 = 30. For "30 is what % of 200?" use (30/200) × 100 = 15%. The calculator handles all common variations automatically.
Can I calculate percentage increases and decreases?
Yes. Use the "Increase/Decrease" mode. The formula is ((New Value - Old Value) / Old Value) × 100. For example, if a price goes from $100 to $120, that's a 20% increase. From $120 to $100 is a 16.67% decrease.
How do I calculate discounts and sale prices?
Use the "Subtract %" mode or switch to our Discount Calculator for more detail. For 25% off $80: enter 25 and 80, result is $60. Or calculate the discount amount with "X% of Y" mode (25% of 80 = $20 off).
What percentage formulas are included?
All common formulas: What is X% of Y, X is what % of Y, percentage of an amount, percentage increase/decrease, add X% to a number, subtract X% from a number. Switch modes using the buttons above the calculator.
Is this calculator accurate for financial calculations?
Yes, the calculator uses standard JavaScript math with floating-point precision suitable for everyday financial calculations like tips, discounts, taxes, and markups. For accounting or scientific precision requiring specific decimal places, verify results match your requirements.
Do my calculations stay private?
Absolutely. All percentage calculations run locally in your browser using JavaScript. No data is transmitted to any server, stored, or tracked. Your numbers remain completely private on your device.