Percentage Calculator
Calculate percentages, parts of a whole, relative change, and reverse base totals with live mathematical proportion visualization.
Understanding Your Results
This calculator has four modes, each answering a different question. Pick the one that matches what you already know and what you're trying to find.
% Of
(Percent ÷ 100) × Number
Finds what a percentage of a number is — e.g. 25% of 200 is 50.
What %
(Part ÷ Whole) × 100
Finds what percent one number is of another — e.g. 50 is 25% of 200.
% Change
|Change ÷ Original| × 100
Finds the percentage increase or decrease between two values.
Find Total
Part ÷ (Percent ÷ 100)
Works backwards from a part and a percentage to find the whole.
Worked Examples
Common Uses of Percentage
Education
Converting marks obtained out of a total into a percentage score.
Shopping
Working out the discount amount and final price on a sale.
Business
Calculating profit margin, markup, or growth between two periods.
Finance
Finding a salary hike, investment return, or year-over-year change.
Tax
Checking GST or other tax percentages added to a base amount.
Everyday
Anything expressed as "X% of Y" — tips, splits, proportions.
Common Mistakes to Avoid
- Don't reverse the numbers. Percentage is obtained ÷ total, not total ÷ obtained — swapping them gives a completely different answer.
- Know whether you want a percentage or a percentage change. "What % is 50 of 200?" and "What's the % change from 50 to 200?" answer different questions with different formulas.
- Convert to a percentage only once. A value already multiplied by 100 shouldn't be multiplied by 100 again — that's a common source of a 100×-too-large result.
References
- Basic arithmetic — percentage concepts
- School-level mathematics standards
Last reviewed July 2026