Why does the result need both fields filled?

Every percentage question involves two known numbers and one unknown; a single input cannot determine anything. Enter both values for your chosen question type and the answer computes immediately.

How do I compute a percentage change (not just a share)?

Use the increase/decrease mode: (new - old) / old × 100. Going from 80 to 100 is +25%; going back from 100 to 80 is -20% — the asymmetry is real and trips up many reports.

What is the difference between percentage and percentage points?

A percentage is a share of a base; percentage points are the arithmetic difference between two shares. Interest moving from 3% to 4% rose one point, but 33% relative.

How do I multiply a percentage by a number, like 0.05 × 2500?

A percent is just a decimal: 0.05 × 2500 = 12.5, the same as 5% of 2500. To use the calculator, enter 5 (%) and 2500 (value) in "what is P percent of Y" mode — the result, 125, is 5% of 2500.

Percentage Calculator — Guide

What is X% of Y? Find a percentage of a number, work out what percent one value is of another, or compute percentage increase and decrease — with the formula shown for each result.

What it is and when to use it

The percentage maths that always needs a second of thought, made explicit: X is what percent of Y, what is P percent of Y, and percentage increase or decrease between two values. Fill the two knowns, read the third — no more re-deriving the formula in your head at the checkout.

Computes percentages between two numbers, percentage increases or decreases, or works backwards from a percentage.

How to use it

Pick the mode matching your question
Enter the known values
Read the result

A worked example

Fill in 42 (%)

Copy this into the tool, or open Percentage Calculator

Questions people ask

Why does the result need both fields filled?: Every percentage question involves two known numbers and one unknown; a single input cannot determine anything. Enter both values for your chosen question type and the answer computes immediately.
How do I compute a percentage change (not just a share)?: Use the increase/decrease mode: (new - old) / old × 100. Going from 80 to 100 is +25%; going back from 100 to 80 is -20% — the asymmetry is real and trips up many reports.
What is the difference between percentage and percentage points?: A percentage is a share of a base; percentage points are the arithmetic difference between two shares. Interest moving from 3% to 4% rose one point, but 33% relative.
How do I multiply a percentage by a number, like 0.05 × 2500?: A percent is just a decimal: 0.05 × 2500 = 12.5, the same as 5% of 2500. To use the calculator, enter 5 (%) and 2500 (value) in "what is P percent of Y" mode — the result, 125, is 5% of 2500.

Next steps

Open the Percentage Calculator tool

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