Choose from eleven modes: percentage increase, decrease, reverse percentage, symmetric percentage difference, part-of-total percentage, percentage value, discount, tax, tip, compound growth and cost markup. Increase, decrease, reverse and difference are placed first in the mode menu for quick access.
Use increase or decrease when a starting value is the reference. Use reverse when the final value and signed change are known. Use symmetric difference when neither value is the reference. For selling-price profit margin rather than cost markup, use the profit margin calculator.
Enter decimal numbers without thousands separators; comma or dot decimals and scientific notation are accepted. Inputs must be finite and within ±1 trillion. Compound periods are whole numbers from 0 to 10,000. Only displayed fields are required. Editing clears the previous result.
Increase, decrease, reverse and difference accept signed values. Increase/decrease require a nonzero starting value and retain its signed denominator. In reverse mode, −20 means a 20% decrease and +20 means a 20% increase. A −100% change has a zero multiplier and no unique original value. Changes below −100% are allowed algebraically and cross zero; they are not ordinary retail discounts.
Part-of-total requires a positive total and nonnegative part. Percentage value, tips and markup use nonnegative inputs. Discount requires a positive original price and a final price between zero and the original. Tax uses a nonnegative before-tax amount and a 0–100% rate. Compound growth requires nonnegative principal and rate.
Calculating preserves the inputs in the URL. Copy the shared link from the result to restore and calculate them on reopening. The link contains entered values.
Change uses (new − old) / old. The old value must be nonzero; negative baselines keep their signed denominator.
Enter a signed change: +20 means a 20% increase; −20 means a 20% decrease. Original = final / (1 + change/100). A −100% change cannot be reversed.
Difference = |A − B| / ((|A| + |B|)/2). Both zero gives 0%; opposite signs give 200%. Swapping inputs does not change the result.
Calculate percentage increase, decrease, reverse percentages and symmetric difference, plus percentage values, discounts, tax, tips and growth.