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Find what percentage one number is of another.
Practical Uses
- Goal Conversion Rate:
What is the conversion rate [X%] for a Premier League striker with 100 [Y] shots and 30 [Z] goals?
30% - Rent Share:
What percentage [X%] of your £3,000 [Y] monthly income goes to £900 [Z] rent in Manchester?
30% - Market Share:
What is a company's market share [X%] if total EV sales are £1,000,000 [Y] and one company sells £250,000 [Z]?
25% - Savings Progress:
What percentage [X%] of your £10,000 [Y] emergency fund have you reached with £7,500 [Z] saved?
75% - Task Completion:
What percentage [X%] of 24 [Y] weekly chores is 18 [Z] completed tasks?
75% - Exam Score:
What is your mark [X%] on a 100 [Y] mark A-Level exam when scoring 85 [Z] marks?
85%
How to Use
- Enter the whole value in the middle box.
- Enter the part value in the third box.
- The percentage result appears instantly in the first box.
- Check "Round" if you want to keep the result to two decimal places.
- Save it to your list with Enter or the "Save calculation" button.
How It Works
The Part-to-Whole Percentage calculator uses this formula:
For example, to find what percentage 25 is of 100, the calculator computes:
So 25 is 25% of 100.
Important Note
When the whole/total value is 0, the percentage is undefined because you cannot divide by zero.
What Is a Part-to-Whole Percentage?
Definition
A part-to-whole calculation answers the everyday question: what percent is X of Y? It converts any fraction into a clean percentage so results are easy to compare across different totals. That’s why grades, battery indicators, and budget charts use percents instead of raw counts. A 90% score means the same achievement whether the test had 10 questions or 100. In budgeting, knowing that rent takes 32% of income is more meaningful than a dollar figure alone. Converting parts to percents normalizes data, highlights outliers, and reveals when something exceeds 100%—a sign that usage or cost is higher than the available whole. It’s a simple move that unlocks quick, fair comparisons without long division on paper, and it quickly exposes whether a claim like “we’re at 150% of goal” reflects healthy overperformance or unrealistic planning. Teachers, analysts, and budget apps lean on this conversion because it travels well across audiences and keeps context intact.
Common Applications
- Grading Tests: Converting a raw score (like getting 45 answers right out of 50 questions) into a final grade percentage (90%).
- Budget Review: Seeing exactly what chunk of your monthly income goes toward rent or groceries to keep your finances in check.
- Progress Tracking: Measuring how much of a project, download, or savings goal you have completed so far.
- Nutrition Ratios: Calculating the percentage of calories in a meal that come from protein versus carbohydrates.
- Customer retention: Checking what percent of users stay subscribed month to month.
- Marketing funnels: Seeing what share of visitors convert to sign-ups or purchases.
Mathematical Context
(Part ÷ Whole) × 100 Take the part, divide by the whole, and multiply by 100. Example: 45 ÷ 50 = 0.90 → 90%. For mental checks, 1/2 is 50%, 1/4 is 25%, 3/4 is 75%. If the part is larger than the whole, the result exceeds 100%, which flags overspending, over-allocation, or growth beyond the baseline. To go the other way—finding the part when you know the percent—multiply the whole by the percent as a decimal. When comparing two scenarios, use the same whole to avoid skewed percents (e.g., comparing ad click-through across campaigns with equal impressions). For running totals, keep track of the whole changing over time; a steady part can shrink as a percent if the whole grows, which is why dashboards recalc percentages continuously.
Need more percentage tools?
- Basic Percentage Calculator
For discounts or taxes. - Original Value Calculator
Reverse a percentage to the original amount. - Percentage Change Calculator
Work out increases or decreases. - Increased Value Calculator
Calculate value after percentage increase. - Decreased Value Calculator
Calculate value after percentage decrease. - Original Before Increase Calculator
Find original amount before percentage increase. - Original Before Decrease Calculator
Find original amount before percentage decrease. - Specialized Calculators (63+)
Practical everyday calculations for real-life scenarios.
Requirements and Important Information
- No installation required – works directly in your browser.
- Compatible with all modern browsers (Chrome, Firefox, Safari, Edge).
- Calculations are performed locally – no data is sent to any server.
- Your saved calculations are stored only on your device.
Each calculator stores up to 20 most recent calculations, automatically removing the oldest entries when this limit is reached. - Works offline after the initial page load.
- Supports both desktop and mobile devices.
- No account or login required.
Helpful Calculator Features
- Instant results that appear as you type—no delays.
- Round toggle to keep results neat (2 decimal places).
- Copy results to clipboard with a single click.
- Saved calculations that persist between sessions.
- Clear visual formulas to understand the maths.
- Mobile-friendly interface that works on all devices.
- Dark mode support for comfortable viewing.
- Keyboard shortcuts for faster calculations.