How do I use the Percentage Calculator?

Enter the values in the fields, press the calculate button, and review the result panel.

Is this calculator free?

Yes. CalcBeacon tools are free to use in your browser.

Should I check the result?

Yes. Use the result as a practical estimate and double-check important financial, health, legal, or work decisions.

CalcBeacon tool

Percentage Calculator

Calculate percentages, percentage change, discounts, markups and ratios with clear formulas and worked examples.

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Calculator

1) What is X% of Y?

Percent (%)

Number

Answer

What this tool helps with

Use this percentage calculator to answer common percentage questions: what is X% of Y, A is what percent of B, and how much a value increased or decreased.

2) A is what percent of B?

Answer

75%

3) Percentage increase or decrease

Original value

New value

Change

25%

This is a percentage increase.

Quick examples

Question

Input

Result

What is 20% of 150?

20 and 150

45 is what percent of 60?

45 and 60

75%

80 to 100

original 80, new 100

25% increase

Quick Guide

Quick answer

Percentage Calculator: A percentage expresses a part of something as a share out of 100. This tool helps with discounts, price changes, grades, conversion rates, markups and everyday comparisons.

Formula / core rulePercentage = part ÷ whole × 100. Percentage change = (new value − original value) ÷ original value × 100.

This is the main calculation rule used by the tool.

Worked exampleIf 45 customers out of 60 completed a form, the completion rate is 45 ÷ 60 × 100 = 75%. If a price moves from £80 to £100, the increase is 25%.

Use the example to check whether your own inputs are in the right range.

Common mistakeDo not swap the part and whole. 20 out of 50 is 40%, but 50 out of 20 is 250%.

This is the most common reason the result can look wrong.

How to interpret the result

A higher percentage means a larger share of the whole. For percentage change, a positive result means increase and a negative result means decrease.

Methodology

The calculator uses the exact values you enter and applies the standard percentage formulas. It does not round until the display stage, so the visible answer is easy to read while the calculation remains consistent.

Important decisions should be checked against payslips, lender documents, tax guidance, official policy or professional advice where relevant.

Reviewed by CalcBeacon Editorial TeamUpdated June 2026Category: Everyday Math & TimeFormula, example and assumptions shown

Practical Guide

How to use this result well

Use this percentage calculator to answer common percentage questions: what is X% of Y, A is what percent of B, and how much a value increased or decreased.

What the result means

A higher percentage means a larger share of the whole. For percentage change, a positive result means increase and a negative result means decrease.

Common mistakes to avoid

Using the sale price as the original price when calculating a discount
Forgetting that percentage change is measured against the starting value
Comparing percentages from different sample sizes without checking the actual numbers

When to double-check

Double-check the result when money, employment rights, borrowing, tax, health or official paperwork depends on the number. CalcBeacon is designed to make the maths clearer, not to replace professional judgement.

Frequently asked questions

How do I calculate 20% of a number?

Multiply the number by 20, then divide by 100. For example, 20% of 150 is 30.

What is the difference between percentage and percentage change?

A percentage shows a share of a whole. Percentage change shows how far a value moved compared with its starting point.

Can I use this for discounts and markups?

Yes. Use percentage-of for a discount amount, then subtract it from the original price. For markups, calculate the percentage increase from cost to selling price.