A fast, free percentage calculator. Find what percent X is of Y, calculate percentage increases or decreases, and solve complex percentage math instantly.
Percentage Calculator
Instant calculations for percentages, fractions, and growth.
Find Percentage
Find Proportion
Percentage Change
How to Calculate Percentages (Formulas)
Understanding the underlying math behind our real-time Percentage Calculator gives you a foundational grasp of statistics. "Percent" literally translates to "per 100". Here are the three primary mathematical formulas utilized by our engine:
What is X% of Y?
Formula to extract a partial value.
Result = (X / 100) × Y
X is what % of Y?
Formula to find the ratio proportion.
Result = (X / Y) × 100
Percentage Change
Formula to calculate growth/decline.
Result = ((New - Old) / Old) × 100
Converting Fractions to Percentages
Fractions and percentages express the exact same mathematical reality. To convert a fraction (like 3/4) into a percentage, you simply divide the top number (numerator) by the bottom number (denominator), which gives you a decimal.
In our example: 3 ÷ 4 = 0.75. You then multiply that resulting decimal by 100 to yield 75%.
Real-World Examples
- Sales Tax & Tipping: If your restaurant bill is $45 and you want to leave an 18% tip, you enter exactly "What is 18% of 45", yielding an $8.10 tip.
- Profit Margins: If you buy a product for $20 originally and sell it for $30 new, you enter those metrics into our Percentage Change tool to see a +50% profit increase.
Frequently Asked Questions
What does a 100% markup mean?
A 100% markup physically means you are doubling the original value. You calculate the initial value, take exactly 100% of it (which is the identical original value), and add it on top. Therefore, a $50 item with a 100% markup now costs requires $100.
How do I calculate a 20% discount quickly?
A smart mathematical trick to rapidly calculate a 20% discount is to realize that 20% represents exactly 1/5th of an object. You can quickly utilize our Percentage Calculator's first mode, or simply multiply the original number by 0.8 (which represents the 80% leftover value you actually have to pay).
The tools and calculators provided on The Simple Toolbox are intended for educational and informational purposes only. They do not constitute financial, legal, tax, or professional advice. While we strive to keep calculations accurate, numbers are based on user inputs and standard assumptions that may not apply to your specific situation. Always consult with a certified professional (such as a CPA, financial advisor, or attorney) before making significant financial or business decisions.
Free Tools Alert
Join 10,000+ creators. Get our newest productivity tools, templates, and calculators directly to your inbox every month.
No spam. One-click unsubscribe.