Percentage Calculator
Three everyday percentage questions, answered instantly: “What percent is X of Y?” (your 43 out of 50 on a test), “What is X% of Y?” (15% of a 200-page reading list), and “What's the percentage change?” (your grade improved from 70 to 84).
Percentage
86%
of the whole
How it works
- Pick a mode: Part of Whole, Percent of Number, or Percentage Change.
- Enter the two known values.
- The answer updates instantly as you type.
- All three modes use the same three elementary percentage formulas.
The formula
Part of whole
percent = (part ÷ whole) × 100
43 of 50 → (43 ÷ 50) × 100 = 86%.
Percent of number
value = (percent ÷ 100) × number
15% of 200 → 0.15 × 200 = 30.
Percentage change
change = ((new − old) ÷ |old|) × 100
70 → 84 is a +20% change.
Worked example
Worked example
- You scored 43 out of 50 on a midterm.
- Part of whole: percent = (43 ÷ 50) × 100 = 86%
86% — a B+ on the standard letter scale.
Common mistakes
- Reversing part and whole — (50 ÷ 43) would give a nonsense 116%.
- Forgetting that percentage change is relative to the starting value.
- Dividing by zero when the whole is 0 — the calculator guards against this.
Frequently asked questions
How do I convert a percentage to a letter grade?
On the common 10-point scale, 90+ is an A, 80+ a B, 70+ a C, 60+ a D. Our grade calculator applies this automatically.
Is percentage the same as CGPA?
No. Percentage is a score out of 100; GPA/CGPA converts letter grades to grade points. Many universities publish conversion tables.
Can I use this for discount math?
Yes — “what is X% of Y” handles discounts directly: 20% of a $50 book is $10 off.
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