Free percentage calculator: percent of a number, percentage change, increase or decrease, discounts and markups. Instant results, no sign-up, any device.
Our percentage calculator handles four of the most common percentage problems instantly. Whether you need to find what 15% of 200 is, determine what percentage 30 is of 200, calculate percent change between two values, or figure out a discount or markup — all four tools are on this page.
Percent of a Number: Type the percentage and the base number. The result appears immediately. Example: 20% of 350 = 70. This is used for calculating sales tax, tips, discounts, and commission.
Percent Change: Enter the starting value and ending value to see the percentage increase or decrease. Formula: ((New − Old) / Old) × 100. A stock rising from $50 to $65 is a 30% increase.
Discount & Markup: Enter the original price and percentage. The calculator shows both the discounted price and the marked-up price simultaneously — useful for retail pricing and sales events.
Every percentage question is one of four calculations. Percent of a number multiplies: X% of Y = Y × (X ÷ 100). What percent divides: (X ÷ Y) × 100. Percent change compares old and new: ((New − Old) ÷ Old) × 100. Discount and markup scale a price: Price × (1 − Rate/100) or Cost × (1 + Rate/100).
20% of 150 = 150 × 0.20 = 30. A price rising from $50 to $65 is a change of ((65 − 50) ÷ 50) × 100 = 30% increase. A $100 jacket at 20% off costs 100 × 0.80 = $80.
To recover the original price, divide rather than add the discount back: Original = Final ÷ (1 − discount%). An item costing $80 after a 20% discount was $80 ÷ 0.80 = $100. Adding 20% to $80 gives $96, which is the common mistake.
If a rate goes from 4% to 5%, it rose 1 percentage point but increased by 25 percent. These are different measures. Interest rates, tax rates and poll results are usually compared in percentage points; growth is reported in percent.
A value that falls 50% needs a 100% rise to return to where it started. $200 dropping 50% is $100; getting back to $200 from $100 is a 100% increase. This asymmetry matters for investment returns, discounts stacked on discounts, and any figure quoted as a percentage swing.