無料パーセント計算機
パーセントを瞬時に計算 — 高速・プライベート・無料。
PercentEase is a free online percentage calculator that solves five types of problems: finding X% of Y, determining what percent X is of Y, calculating percentage change, finding the whole from a known part and percentage, and computing increase or decrease by a percentage. All calculations run instantly in your browser with no data collected. Available in 20 languages with no sign-up required.
How Do You Use PercentEase?
- 1
Choose Your Calculation Mode
Select from five modes: find X% of Y, determine what percent X is of Y, calculate percentage change, reverse-solve, or increase/decrease by a percentage.
- 2
Enter Your Numbers
Type your values into the input fields. Results appear instantly as you type.
- 3
Copy Your Result
Your answer appears immediately below the inputs with the formula and calculation shown.
Common Percentage Calculations
| Problem | Answer |
|---|---|
| What is 10% of 100? | 10 |
| What is 15% of 200? | 30 |
| What is 20% of 50? | 10 |
| What is 25% of 80? | 20 |
| What is 30% of 150? | 45 |
| What is 50% of 60? | 30 |
| 15 is what % of 75? | 20% |
| 7 is what % of 28? | 25% |
| Change from 40 to 50 | 25% increase |
| Change from 200 to 150 | 25% decrease |
| What is 12.5% of 400? | 50 |
| 45 is what % of 180? | 25% |
Real-World Percentage Examples
Restaurant Tip
Your dinner bill is $65. You want to leave an 18% tip.
Tip = $65 × 18 ÷ 100
$11.70
Sale Discount
A jacket costs $120 and is 35% off.
Discount = $120 × 35 ÷ 100
You save $42 — pay $78
Test Score
You scored 42 out of 50 on an exam.
Grade = (42 ÷ 50) × 100
84%
Price Change
Gas went from $3.20 to $3.84 per gallon.
Change = (($3.84 − $3.20) ÷ $3.20) × 100
20% increase
Fraction ↔ Decimal ↔ Percentage
| Fraction | Decimal | Percentage |
|---|---|---|
| 1/2 | 0.5 | 50% |
| 1/3 | 0.333 | 33.33% |
| 2/3 | 0.667 | 66.67% |
| 1/4 | 0.25 | 25% |
| 3/4 | 0.75 | 75% |
| 1/5 | 0.2 | 20% |
| 2/5 | 0.4 | 40% |
| 3/5 | 0.6 | 60% |
| 4/5 | 0.8 | 80% |
| 1/8 | 0.125 | 12.5% |
| 3/8 | 0.375 | 37.5% |
| 1/10 | 0.1 | 10% |
パーセントを理解する
パーセントは100の分数として表された数値です。「パーセント」という言葉はラテン語の「per centum」（百あたり）に由来します。
クイック例
- • 150の20%は？→ 30
- • 15は60の何%？→ 25%
- • 50から75への変化 → 50%増加