Percentage calculator

This tool covers four different calculation modes. Mode 1 answers "What is X% of a number?" — for example, what is 15% of 200. Mode 2 answers "What percentage does A represent of B?" — useful for finding what fraction of a total a given part represents. Mode 3 calculates the percentage change between two values, showing whether there was an increase or a decrease and by how much. Mode 4 adds or subtracts a percentage from a base value, making it ideal for calculating prices with tax, trade discounts, or any proportional adjustment.

Use Mode 4 and select the Subtract operation. Enter the original price in the "Base value" field and the discount percentage in the "Percentage" field. The calculator will show you the discounted price, the discount amount separately, and the final price to pay. For example, if an item costs 80 and has a 25% discount, the result will be 60, with a saving of 20.

They are two different operations. Applying a percentage (Mode 4) takes a base value and increases or decreases it by a fixed proportion: if the base is 100 and you add 20%, you get 120. Percentage change (Mode 3), on the other hand, measures how much a value changed between two points in time: if something went from 100 to 120, the change was +20%. Even though the numbers match in this example, the direction is opposite: in one case you start from the percentage to find the result; in the other you start from two values to find the percentage.

Because each operation uses a different base. Start with 100 and increase by 20%: you get 120. Now remove 20% from that new value: 120 × 0.20 = 24, and 120 − 24 = 96, not 100. The 20% of 120 is larger than the 20% of 100, so subtracting the same percentage from the already-increased value always lands slightly below the starting point. To get back to exactly the original, you would need to subtract the inverse equivalent percentage — in this case approximately 16.67%.

Everyday uses are countless. When shopping, to calculate the real price of an item on sale before deciding to buy. In personal finance, to compare returns on different investments or understand how savings grow month by month. At work, to express targets met, budget variations, or differences between periods. In education, to convert scores into grades: if you score 54 out of 70, the calculator tells you that is 77.1%. In nutrition and fitness, to know what percentage of daily calories comes from protein, carbohydrates, or fat. Essentially, in any context where a number needs to be expressed as a proportion of another.

Salespeople and merchants use it to calculate margins, commissions, and discounts instantly without relying on a spreadsheet. Accountants and managers use it to analyze period-over-period changes and review financial statements quickly. Teachers and students use it to convert grades and understand proportions in exercises. Marketing professionals calculate conversion rates, audience growth, and return on investment between campaigns. Nutritionists and personal trainers use it to distribute macronutrients according to calorie targets. Shoppers and everyday consumers consult it to avoid being misled by deceptive discounts or to compare real prices at the store.

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