You need a general percent calculation and want the formula and base number made explicit.
Percentage Calculator
Calculate percent of a number, percentage change, discount percentage, part-of-total questions, and percentage-point differences in your browser.
Start here
Choose the calculation mode.
Browser-first
Your numbers are calculated locally in your browser and are not uploaded to a server.
Useful for
Calculate completion rates
Common scenarios
Result12.50%
25 is 12.50% of 200.
Use caseA is what % of B
Useful for completion rates, share of total, scores, and proportions.
Formula: A / B x 100 Quick answer
Solve the percentage question you actually have
Choose percent of a number, part as a percent of total, percentage change, discount percentage, or percentage-point difference, then enter the matching values.
Percent change and percentage-point change answer different questions; selecting the wrong mode can produce a plausible but misleading result.
Discount Calculator: Calculate final price, amount saved, total discount percentage, coupons, optional second discounts, and shipping in your browser.
About this tool
Calculate percent of a number, percentage change, discount percentage, part-of-total questions, and percentage-point differences in your browser.
Your numbers are calculated locally in your browser and are not uploaded to a server.
How to use it
- Choose the calculation mode.
- Enter value A and value B.
- Read the result and explanation below the inputs.
Common use cases
- Calculate completion rates
- Find percent of a number
- Compare increases or decreases
- Check discount percentage
- Quickly verify report, sales, or classroom percentages
Common Percentage Questions
Percentage searches often come from practical comparison tasks. Choose the mode that matches the question rather than trying to rewrite the formula yourself.
| Question | Mode to use | Example |
|---|---|---|
| What percent is A of B? | A is what % of B | 25 is 12.5% of 200. |
| What is A% of B? | What is A% of B | 25% of 200 is 50. |
| How much did it change? | Percentage change | From 200 to 250 is a 25% increase. |
| How large is the discount? | Discount percentage | 1000 to 790 is 21% off. |
Percentage Formula Examples
Use the examples below to match the wording of your question to the right calculation mode.
| Question wording | Formula idea | Example result |
|---|---|---|
| A is what percent of B? | A / B x 100 | 30 of 120 = 25% |
| What is A percent of B? | B x A% | 15% of 80 = 12 |
| What is the percent increase? | (New - Old) / Old x 100 | 80 to 100 = 25% increase |
| What percent off is this? | (Original - Sale) / Original x 100 | $50 to $40 = 20% off |
Percent Versus Percentage Points
A common mistake is mixing up a percent change with a percentage-point change. If a rate moves from 40% to 45%, the direct difference is 5 percentage points. The relative increase is 12.5% because 5 is 12.5% of 40.
| Change | Percentage-point difference | Relative percent change |
|---|---|---|
| 40% to 45% | 5 points | 12.5% increase |
| 10% to 15% | 5 points | 50% increase |
| 80% to 60% | 20 points | 25% decrease |
Choose the Right Base Number
Most percentage mistakes come from using the wrong base number. Before calculating, identify which value is the whole, original, or comparison base.
| Question | Base number | Why it matters |
|---|---|---|
| What percent is 30 of 120? | 120 | The total is the denominator. |
| Price increased from 80 to 100 | 80 | Percent change is compared with the original value. |
| Price dropped from 100 to 75 | 100 | Discount percent is based on the original price. |
| A rate changed from 40% to 45% | 40% | Use percentage points for the direct difference; use 40% for relative change. |
FAQ
Can it calculate percentage change?
Yes. Choose percentage change and enter the original and new values.
Can it calculate discounts?
Yes. Choose discount percentage and enter the original and sale prices.
What is the difference between percent and percentage points?
A percent is a relative comparison. Percentage points are the direct difference between two percentages, such as 40% to 45% being a 5 percentage-point increase.
Are my numbers uploaded?
No. The calculation runs in your browser.