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Find a percentage, calculate a change, compare values, or work out a sale price. Choose a mode and Axiom shows each step.
Choose a mode: percent of a number, increase, decrease, percentage difference, or discount. Enter the two values using the labels for that mode and press Solve step-by-step to see the answer and calculation.
A percentage is a fraction out of 100: p% of a value is value × p/100. Increase adds that amount to the original; decrease and discount subtract it. Percentage difference compares two nonnegative values using their absolute difference divided by their average, then multiplied by 100—it is not a change measured from one starting value.
Choose What is X% of Y?, enter 25 as the percent and 80 as the number. Calculate 80 × 25/100 = 20.
Choose Discount calculator and enter an original price of 120 and discount of 15. Savings = 120 × 0.15 = 18; sale price = 120 − 18 = 102, before any tax or delivery charges.
Choose Percentage difference and enter 40 and 60. Difference = 20; average = 50; 20/50 × 100 = 40%. Swapping the values gives the same answer.
Change uses a starting value as its reference. Difference uses the average of two values and is symmetric. This tool’s increase/decrease modes apply a known rate; they do not infer the rate from old and new amounts.
Percent-of mode allows signed percentages and numbers. Increase requires a nonnegative rate; decrease and discount require a rate from 0% to 100%. Percentage difference requires nonnegative values, with at least one above zero.
Not in this calculator. A 100% discount makes the price zero; larger discounts are rejected. Increase, decrease, and discount also require a positive original amount.
That is not a separate mode here. Divide the part by the whole and multiply by 100 in the General Calculator: 20 ÷ 80 × 100 = 25%.
Use the General Calculator for a custom percentage expression or the Interest Calculator for growth over time. The percentages lesson connects rates, fractions, and everyday price changes. Related tools: General Calculator, Interest Calculator. Read the discount example in the percentages lesson or practice percentages to build confidence without relying on a calculator.