Free Percentage Calculator – Calculate % Change, X% of Y, Increase & Decrease
Work out percentage increase/decrease, find X% of Y, or see what percent one number is of another. Fast, accurate, and mobile-friendly.
⚠️ Advisory only: Results are for guidance. For tax, finance, grades or contracts, confirm with a qualified professional or official source.
Percentage Calculator
Your result will appear here
Enter two known values and choose what to find.
Why use this Percentage Calculator?
Multiple modes
X% of Y • What % is X of Y • % increase/decrease • % difference.
Smart rounding
Control decimal places and see exact math.
Step-by-step breakdown
We show the formula and each calculation step.
Shareable
Copy a link that preserves your inputs and result.
How to Use the Percentage Calculator: Step-by-Step Guide
Choose a mode
e.g., % change, X% of Y.
Enter your numbers
Use decimals if needed.
Read the result
Plus a step-by-step breakdown.
Why Use Our Percentage Calculator? Key Features & Benefits
Understanding Percentage Math: What You Need to Know
A percentage is a ratio “per hundred.” Common tasks include finding a portion of a value, reversing the calculation to find what percent one number is of another, and measuring the relative change between two values. This tool handles all three with clear formulas and a worked breakdown.
Formulas Explained with Worked Examples
- X% of Y:
result = (X / 100) × Y - What percent is A of B?
percent = (A / B) × 100% - % increase from Old to New:
((New − Old) / Old) × 100% - % decrease from Old to New:
((Old − New) / Old) × 100% - % difference between A and B (symmetric):
(|A − B| / ((A + B)/2)) × 100%
Worked example: Price was £80, now £92 → % increase = ((92 − 80) / 80) × 100% = 15%. Another example: 25% of 140 = (25/100) × 140 = 35.
Rounding: Money usually to 2 decimals; grades might use 1; engineering results may need more.
Frequently Asked Questions About Percentages
What Our Clients Say About Our Calculators
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This estimator feels like a mini financial advisor. It’s incredibly helpful for first-time buyers to understand their limits. The income-to-debt ratio logic is spot on.
This tool is a lifesaver for budgeting. It’s intuitive and gives a clear breakdown of monthly payments. I especially like the amortization summary—it’s great for planning long-term.
Simple, fast, and accurate. The BMI Calculator gives instant results with clear health categorization. I appreciate the clean layout and mobile responsiveness—it’s perfect for quick checks on the go
Information on this page is for education only and is not a substitute for professional financial or tax advice.