Tool 09 / Everyday
Percentage Calculator
Work out a percentage of a number, what fraction one number is of another, percentage change, and percentage difference — with the working shown so you can check it.
What is X% of Y?
Must not be zero.
25% of 400 is 100
25% of 400 = (25 ÷ 100) × 400
- 1Convert the percentage to a decimal: 25 ÷ 100 = 0.25.
- 2Multiply by the base value: 0.25 × 400 = 100.
Worked example: 25% of 400 = 100. A change from 800 to 1,000 is (200 ÷ 800) × 100 = 25% increase. Percentage difference uses the average of both values instead of a baseline.
Manual
04 stepsHow to use it
- 01Pick a mode: percent of a value, share of total, change, or difference.
- 02Enter the two numbers in the labelled fields.
- 03Read the result plus the formula showing how it was calculated.
- 04Switch modes to reuse the same numbers for comparison.
Example
What it looks like
- Input
- Price rose from ₹800 to ₹1,000
- Output
- Increase of ₹200 = 25% increase
The base for a change is the original value: 200 ÷ 800 = 0.25.
Method
How it works
Percentage of a value multiplies the value by the percentage and divides by 100. 'What percent' divides the part by the whole and multiplies by 100.
Percentage change compares an old and new value: (new − old) ÷ old × 100. Negative results mean a decrease. Percentage difference compares two values without treating either as a baseline: |a − b| ÷ ((a + b) ÷ 2) × 100.
Knowing which base is used prevents most percentage errors. A 20% discount followed by 20% off again is 36% off in total, not 40%, and a 50% fall needs a 100% rise to recover.
FAQ
Before you ask
Specific to percentage calculator, including limits and privacy.
What is the difference between percentage change and percentage difference?
Change has a clear before and after, so the earlier number is the base. Difference compares two values of equal status, so the average of both is used as the base.
How do I add or remove GST using percentages?
Add tax with value × (1 + rate ÷ 100). Remove inclusive tax with value ÷ (1 + rate ÷ 100). The GST Calculator handles the rounding for you.
Can I enter negative numbers?
The share and percent-of modes expect non-negative values. Percentage change accepts an increase or decrease, so direction matters more than sign.
Why is percentage difference always positive?
It measures the size of the gap regardless of direction. Use percentage change when direction matters.
Privacy
Calculations run locally; no inputs are sent or saved.
Read the privacy policy for data retention, analytics and contact details.
Limits
Results depend on the input you provide and your browser. Always sanity-check important numbers before publishing or billing.
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