X is What Percent of Y Calculator
To find what percent one number is of another, divide the part by the whole and multiply by 100: percent = part ÷ whole × 100.
Last updated 2026-08-14
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quizExample
How this calculator works, with real numbers (no JavaScript needed):
Inputs
- The part (X)
- 30
- The whole (Y)
- 200
Results
- Percentage
- 15%
- The part (X)
- 30
functionsThe formula
The question "X is what percent of Y?" asks you to express one number as a proportion of another. It's everywhere: test scores, budget splits, survey results, class attendance.
The formula
Percent = part ÷ whole × 100
Worked example
30 is what percent of 200?
30 ÷ 200 × 100 = 0.15 × 100 = 15%
So 30 is 15% of 200.
Why it works
A percentage is a fraction out of 100. You're asking "what fraction of 200 is 30?" — that's 30/200 = 0.15, which is 15/100 = 15%. Dividing and multiplying by 100 converts the fraction into a percentage.
Everyday uses
- Scores — "34 out of 40 is what percent?" → 34 ÷ 40 × 100 = 85%
- Attendance — "I attended 42 of 50 classes" → 42 ÷ 50 × 100 = 84%
- Budgeting — "rent of ₹12,000 out of ₹40,000 salary" → 30%
- Surveys and polls — 450 of 1,000 respondents = 45%
The other directions
This calculator does part → percent. If instead you know the percent and want the part, that's the main percentage calculator. If you know the percent and part but not the whole, use the reverse percentage calculator.
helpFrequently asked questions
question_mark30 is what percent of 200?
30 ÷ 200 × 100 = 15%. So 30 is 15% of 200.
question_markHow do I find what percentage one number is of another?
Divide the part by the whole and multiply by 100. For example, 34 out of 40 = 34 ÷ 40 × 100 = 85%.
question_markWhat is the formula for percentage of a total?
Percent = part ÷ total × 100. This is the standard "what percentage" formula.