Find what X% of Y is, calculate percentage increase, or percentage decrease — instantly, no signup required.
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Percentages appear in almost every area of daily life — discounts, tax rates, tips, exam scores, salary changes, investment returns, and statistical data. This percentage calculator works as a percent of a number calculator, percentage change calculator, and percent increase and decrease tool for students, professionals, shoppers, and analysts.
The most common use case is finding X% of Y — for example, calculating a 20% discount on a £250 item, or figuring out how much to tip on a restaurant bill. Enter the percentage and the base number and the result appears instantly without needing to remember the formula or use a scientific calculator.
Percentage increase and decrease calculations are essential for comparing values over time. Sales teams use them to measure revenue growth between quarters. Students use them to calculate grade changes between assignments. Investors use them to track portfolio performance. The formula for percentage increase is ((new − old) / old) × 100, and for decrease it is ((old − new) / old) × 100 — this tool applies those formulas automatically so you get an accurate answer without doing the arithmetic manually.
Shoppers use percentage calculators when comparing sale prices — if a £180 jacket is reduced to £135, how much is that as a percentage discount? Enter 180 as the old value and 135 as the new value in the Percentage Decrease section and you get the answer (25%) instantly. Professionals in finance, marketing, and operations use the same calculations daily to track KPIs, measure conversion rates, and report on performance changes across time periods. All three calculators on this page run entirely in your browser — no data is sent anywhere.