Use this percentage calculator to find what percentage one number is of another. Enter the part and the whole to get an instant percentage result.
This tool is useful for checking test scores, discounts, savings goals, business progress, budget categories, and any situation where you need to compare one amount with a total.
How to use the Percentage Calculator
- Enter the smaller amount or the part you want to compare.
- Enter the total amount or whole.
- Select Calculate Percentage.
- Read the result as the percentage that the part represents of the whole.
For example, if you scored 18 marks out of 72, enter 18 as the part and 72 as the whole.
Percentage calculation example
Suppose you completed 18 tasks out of a total of 72 tasks.
18 is what percentage of 72?
The calculation is:
18 / 72 x 100 = 25%
So, 18 is 25% of 72.
Percentage formula
To find what percentage one number is of another, divide the part by the whole and multiply the result by 100.
Percentage = Part / Whole x 100
The part is the amount you are measuring. The whole is the total amount you are comparing it against.
Common uses for percentages
Percentages make comparisons easier because they show an amount as a share of 100.
You can use this calculator to:
- Calculate a test score or exam result
- Check the percentage of a budget spent on one category
- Measure progress toward a goal
- Compare sales, conversions, or completed tasks
- Find the percentage of a discount
- Work out a down payment as a percentage of a home price
- Compare an amount with a total quantity
Percentage examples in everyday life
Test score
If you answer 42 questions correctly out of 50:
42 / 50 x 100 = 84%
Your score is 84%.
Monthly budget
If you spend $900 on rent from a monthly income of $3,000:
900 / 3,000 x 100 = 30%
Rent uses 30% of your monthly income.
Savings goal
If you have saved $2,500 toward a $10,000 goal:
2,500 / 10,000 x 100 = 25%
You have reached 25% of your savings goal.
Important input rules
The whole value cannot be zero because division by zero is not possible.
The calculator works with positive and negative numbers, but consider whether a negative percentage makes sense for your situation. For most everyday uses, such as test scores, budgets, discounts, and progress tracking, use positive numbers.
Also make sure the part and whole use the same unit. For example, do not compare dollars with pounds, or centimetres with metres, unless you convert them first.
Percentage calculator and percentage change
This calculator answers one question:
What percentage is one number of another?
It does not calculate percentage increase or percentage decrease. Percentage change needs a starting value and a new value, and it uses a different formula.
For example, moving from $80 to $100 is a $20 increase. The percentage increase is calculated from the original $80 value, not the new $100 value.
Frequently asked questions
This calculator finds what percentage one number is of another, but a sale price needs one extra step. For
20% off $80: find 20% of 80 ($16), then subtract you pay $64. The general pattern is: discount amount =
original × (percent ÷ 100), then subtract that from the original price.
Same idea in reverse. For 8% tax on $50: find 8% of 50 ($4), then add total $52. The shortcut is to
multiply by 1 + (percent ÷ 100), so $50 × 1.08 = $52. One multiplication, no separate steps.
A classic mix-up. If a rate rises from 10% to 15%, that’s a 5 percentage-point increase but a 50 percent
increase relative to where it started (5 ÷ 10 × 100). News headlines usually mean percentage points, so
always check which one is meant before comparing two figures.
Absolutely. Percentages over 100% just mean the part is bigger than the whole you’re comparing against
150 out of 100 is 150%. You’ll see this with growth figures (“sales are 130% of last year”) or whenever
the “whole” is a target rather than a maximum.
This calculator doesn’t do percentage change directly it needs a different formula, as the page notes.
Take (new value − old value) ÷ old value × 100. Moving from $80 to $100: (100 − 80) ÷ 80 × 100 = a 25%
increase. Note it’s always divided by the original value, not the new one.
Related tools
Use the Budget Planner to see how different expenses compare with your monthly income.
Use the Mortgage Calculator to estimate a home-loan payment, then use this calculator to work out your down payment percentage.
Use the Unit Converter when you need to convert measurements before comparing values.
Read our full guide: What Percent Is a Number of Another Number? Formula + Examples
Reviewed by ToolsByMeh
Last reviewed: September 21, 2026
Methodology: Percentage = part divided by whole, multiplied by 100.