What is a Percentage Calculator?
A percentage calculator helps you solve the four most common percentage-related maths problems instantly. Whether you need to know what 15% of 200 is, what percentage 30 is of 150, how much a price increased from $80 to $95, or what a 20% discount saves you on a $250 item — our tool handles all four calculations with dedicated input panels, so you never have to remember the formula.
Percentages are used in virtually every area of daily and professional life: calculating discounts and sale prices, working out tax amounts (VAT, sales tax), evaluating investment returns, interpreting statistical data, grading academic papers, and analysing website conversion rates. Understanding and quickly computing percentages is a fundamental numeracy skill, and this tool makes it effortless for students, business professionals, and everyday users.
How to Use the Percentage Calculator
- What is X% of Y? — Enter the percentage and the base value; get the result (e.g. 15% of 200 = 30).
- X is what % of Y? — Enter the part and the whole; get the percentage (e.g. 30 of 200 = 15%).
- Percentage Change — Enter the original and new value; get the % increase or decrease.
- Increase/Decrease by % — Enter a value and a percentage; apply it as an increase (+) or decrease (−).
Why Use Our Percentage Calculator?
- 100% Free — No cost, no limits.
- No Registration — No account needed.
- Browser-Based — Instant calculations happen client-side.
- Four Calculators in One — All major percentage problem types covered.
- Live Results — Results update as you type — no need to click a button.
Frequently Asked Questions
Percentage increase = ((New Value − Old Value) ÷ Old Value) × 100. For example, if a price rose from $80 to $100, the increase is ((100 − 80) ÷ 80) × 100 = 25%. Use the "Percentage Change" calculator on this page — enter the old value in "From" and the new value in "To" for the instant result.
Use the "Increase/Decrease by %" calculator. Enter the original price, the discount percentage, and select "−" (decrease). The result is the discounted price. For example, $250 with a 20% discount: 250 − (250 × 0.20) = $200. Alternatively, use "What is X% of Y?" to find the discount amount, then subtract it from the original price.
Use the "Increase/Decrease by %" calculator. Enter the pre-tax price, enter the tax rate (e.g. 20 for 20% VAT), and select "+" (increase). The result is the total price including tax. For example, £100 + 20% VAT = £120. To find just the tax amount, use "What is X% of Y?" — enter 20% of 100 = £20.
Percentage change = ((New − Old) ÷ |Old|) × 100. A positive result indicates an increase; a negative result indicates a decrease. The formula always divides by the absolute value of the original number to handle cases where the original value is negative (common in financial analysis where values can go from negative to positive).