Percentage Calculator

Calculate percentages online for everyday math: find a percent of a number, work out percentage increase or decrease, compare two values, reverse a discount, and average multiple percentage scores without switching tools.

Quick formula

Percentage = part / whole x 100

Percent Calculator

Instant

What do you want to calculate?

Choose the percentage question that matches your problem. Labels update for each mode.

Percentage

Value

Result

Formula

Inputs

Difference

Quick check

Percentage Calculator Examples

Load a common scenario to see the formula, result, and interpretation. These examples match frequent searches for percentage increase, discount percentage, and reverse percentage calculations.

What is 15% of 240?

A standard percent-of-number calculation. The result is 36 because 240 x 0.15 = 36.

Percentage increase from 80 to 100

Useful for price changes, growth, grades, or metrics. The increase is 25% because the change is 20 on an 80 base.

25% discount on 120

A discount percentage calculator removes the saved amount from the original price. Here, 25% off 120 leaves 90.

Reverse a 20% decrease

If 80 is the value after a 20% decrease, divide by 0.8 to find the original value of 100.

Percentage Calculator Formulas

Most percent problems are simple once the base number is clear. The formulas below are shown in crawlable text so you can verify each result.

Percent of a number

Result = Number x Percent / 100

Use this for questions like what is 15 percent of 240.

Part as percent of whole

Percentage = Part / Whole x 100

Use this when you know the part and total, such as 18 out of 60.

Percentage increase or decrease

Percent change = (New - Original) / Original x 100

Positive values are increases. Negative values are decreases.

Discount percentage

Final price = Original price x (1 - Discount % / 100)

Use this for sale prices, coupons, and markdowns before tax or fees.

Reverse percentage

Original value = Final value / (1 + Percent change / 100)

Use this when a value already includes an increase, decrease, tax, or discount.

Average percentage

Average percentage = Points earned / Points possible x 100

Use weighted points instead of averaging individual percentages when point totals differ.

How to Use the Percentage Calculator

Pick the exact question first. The same two input boxes can solve several different percentage problems.

Choose a mode

Select percent of a number, percentage change, discount, reverse percentage, or average percentage.

Enter the two values

Use plain numbers. For 15%, enter 15 rather than 0.15. Negative percentages are allowed where they make sense.

Read the result and formula

The result panel shows the answer, the formula used, and a quick check so the math is easy to audit.

Compare edge cases

Check zero, negative, discount, and reverse percentage notes before using the answer in pricing, grading, or reporting.

Percentage Reference Table

These common cases show which formula to use and what each input means.

Use case	Input example	Formula	Result
Percent of a number	15% of 240	240 x 15 / 100	36
Part of whole	18 out of 60	18 / 60 x 100	30%
Percentage increase	80 to 100	(100 - 80) / 80 x 100	25%
Discount price	25% off 120	120 x (1 - 25 / 100)	90
Reverse percentage	80 after -20%	80 / (1 - 20 / 100)	100

Percentage Calculator Edge Cases

Percent math is small, but the meaning can change when the base value, sign, or weighting changes.

Zero as the base

You cannot calculate percentage change from zero because the formula divides by the original value. Describe the change as an absolute difference instead.

Negative values

Negative numbers can be valid in finance or temperature changes, but the interpretation depends on context. Confirm whether the base should be signed or absolute.

Reverse discounts

If a final price is after 20% off, divide by 0.8. Do not simply add 20% back, because 20% of the lower final price is smaller.

Average percentages

When categories have different point totals, calculate total earned points divided by total possible points instead of averaging separate percentages.

Rounding

The calculator rounds display values for readability. Use the formula line when you need to audit the exact relationship between inputs.

Discounts before tax

Retail discounts are usually applied before sales tax, shipping, and platform fees. Use the final checkout amount for real purchase comparisons.

Percentage Calculator FAQ

Direct answers to common percentage questions, including percent change, reverse percentage, discounts, and averages.

Multiply the number by the percentage divided by 100. For example, 15% of 240 is 240 x 15 / 100 = 36.

Divide the part by the whole, then multiply by 100. If 18 is the part and 60 is the whole, the percentage is 18 / 60 x 100 = 30%.

Subtract the original value from the new value, divide by the original value, then multiply by 100. A move from 80 to 100 is a 25% increase.

Use the same percent change formula: (new value - original value) / original value x 100. A negative result means the value decreased.

Divide the final value by 1 minus the discount rate. If 80 is the price after 20% off, the original price is 80 / 0.8 = 100.

A simple average is only accurate when each percentage has the same weight. If the underlying totals differ, add the earned points and possible points, then calculate one overall percentage.

Yes. Choose discount mode, enter the original price and percent off, and the calculator returns the final price and amount saved before tax or fees.

Percent is relative to a base. Percentage points are absolute differences between two percentages. Moving from 20% to 25% is a 5 percentage point increase, but a 25% relative increase.

Ready to calculate a percentage?

Choose the percentage question that matches your problem, enter two values, and use the formula line to verify the answer.

Jump to calculator