Important Note : Percent problems always connect three values: part, whole, and percent

Use this Percentage Calculator to solve the three most common percent problems in one place: finding a percentage of a number, finding what percent one number is of another, and finding the whole when a part and percent are known. It is useful for discounts, markups, grades, finance, shopping, and everyday math.

Reviewed by: AjaxCalculators Editorial Team
Last updated: April 23, 2026
Method source: Standard percent relationships between part, whole, and percent
Editorial standards: AjaxCalculators Editorial Policy

What This Percentage Calculator Calculates

This calculator solves three core percentage questions:

• Mode 1: How much is p% of x?
• Mode 2: x is what percent of y?
• Mode 3: x is p% of which number?

These three modes cover most everyday percent calculations.

How the Percentage Calculator Works

All percent problems are based on the same core relationship:

Part = Percent × Whole

When using this formula in calculator form, the percent must be written as a decimal.

For example:

• 25% = 0.25
• 8% = 0.08
• 150% = 1.50

Mode 1: How much is p% of x?

This mode finds the part when the percent and whole are known.

y = x × (p / 100)

Example:

15% of 330 = 330 × 0.15 = 49.5

Mode 2: x is what percent of y?

This mode finds the percent when the part and whole are known.

p = 100 × x / y

Example:

30 is what percent of 150?
p = 100 × 30 / 150 = 20%

Mode 3: x is p% of which number?

This mode finds the whole when the part and percent are known.

y = 100 × x / p

Example:

30 is 20% of which number?
y = 100 × 30 / 20 = 150

Assumptions and Important Notes

• Enter the percent as a normal percentage number, so 20 means 20%, not 0.20.
• If the whole is zero, the “what percent” form becomes undefined.
• If the percent is zero, the “find the whole” form becomes undefined.
• Percent means “per hundred,” so every percentage calculation is really a ratio based on 100.

Worked Examples

Example 1: Find p% of a Number

Suppose you want to find 18% of 250.

Step 1: Convert 18% to decimal form
18% = 0.18

Step 2: Multiply by the whole
0.18 × 250 = 45

So 18% of 250 = 45.

Example 2: Find What Percent One Number Is of Another

Suppose you want to know 45 is what percent of 180.

Step 1: Divide the part by the whole
45 ÷ 180 = 0.25

Step 2: Convert to percent
0.25 × 100 = 25%

So 45 is 25% of 180.

Example 3: Find the Whole from a Part and Percent

Suppose you know 60 is 15% of a number.

Step 1: Use the whole formula
y = 100 × x / p

Step 2: Substitute the values
y = 100 × 60 / 15

Step 3: Calculate
y = 400

So 60 is 15% of 400.

How to Use This Percentage Calculator

1. Choose the mode that matches your question.
2. Enter any two known values.
3. Let the calculator solve the missing third value.
4. Check the result and the matching formula shown by the tool.

How to Interpret the Result

Mode 1 gives you the part of a whole.

Mode 2 gives you the percentage relationship between two values.

Mode 3 gives you the original whole from a known part and percent.

If the result looks too big or too small, check whether you entered the percentage as a percent number rather than as a decimal.

Practical Uses of a Percentage Calculator

• find discounts and sale prices
• calculate markups and commissions
• work out grades and test scores
• compare values in finance and business
• solve general homework and daily-life percent problems

References

1. OpenStax: part = percent × total and percent relationships
2. OpenStax: converting percents to decimals and back

Related Calculators

• Average Percentage Calculator
• Percentage of a Percentage Calculator
• Percentage Change Calculator
• Percentage Decrease Calculator
• Fraction to Percentage Calculator

Disclaimer: This calculator is for educational and general calculation use. The key idea behind every mode is the same: percentage problems connect a part, a whole, and a percent.