数学

パーセント計算機

割合・増減率・ある数の何%かを計算

Calculate what a percentage of a number is

What is
%
of
15% of 200 = 30
使い方

Choose the calculation mode from the tabs above:

  • X% of Y — Find a percentage of a number (e.g., 15% of 200 = 30)
  • X is what % — Find what percentage X is of Y (e.g., 30 is 15% of 200)
  • % change — Find the percentage increase or decrease between two values
  • X + Y% — Add or subtract a percentage from a number (e.g., 100 + 20% = 120)

計算式

Percentage formulas:

P% of N = (P ÷ 100) × N
X is what % of Y = (X ÷ Y) × 100
% change = ((New − Old) ÷ Old) × 100
Add P% to N = N × (1 + P/100)
Subtract P% from N = N × (1 − P/100)

Calculating percentages is a common task in daily life, from figuring out a tip at a restaurant to determining the discount on a sale item or calculating profit margins. A percentage represents a fraction of 100, making it easier to compare proportions. Knowing how to quickly find percentage increases or decreases is a highly practical mathematical skill. For a deeper dive into the concept, read about Percentages on Wikipedia.