このガイドは英語で提供されています。
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.
変化率は（新値 − 元値）/ 元値です。元値は零以外とし、負の元値も符号付き分母のまま計算します。
+20 は 20% 増、−20 は 20% 減です。元値 = 最終値 /（1 + 変化率/100）。−100% は逆算できません。
対称差は |A − B| / ((|A| + |B|)/2)。両方零なら 0%、異符号なら 200%。入力を交換しても同じです。
割合の増減、元値の逆算、対称百分率差に加え、割合の値・割引・税額・チップ・複利成長・値上げを計算します。