What percentage calculations does this do?

Three main forms: X% of Y (e.g. 20% of 50), X is what percent of Y (e.g. 10 is what % of 50), and percentage change (X→Y increase/decrease). Plus tip-style add-on percentage.

How do I calculate a percentage increase?

(New − Old) ÷ Old × 100. Example: from 50 to 65 is (65−50)/50 × 100 = 30% increase.

Is a 50% decrease then 50% increase back to original?

No. 100 → 50% decrease → 50, then 50% increase → 75 (not 100). Percentage changes don't reverse symmetrically — a common source of error.

Percentage Calculator 2026 — Free Online Tool

About the Percentage Calculator

The Percentage Calculator covers the four most common percentage problems: finding a percentage of a number, expressing one number as a percentage of another, calculating percentage change between two values, and adding or removing a percentage from a value (useful for VAT, discounts and markups). All calculations run entirely in your browser — no data is stored or shared.

The Four Percentage Calculations

Percentage of a number — "What is 15% of €240?" → €36. Formula: (percentage ÷ 100) × number
Number as a percentage — "35 is what % of 175?" → 20%. Formula: (part ÷ whole) × 100
Percentage change — "A price rose from €50 to €65 — what is the % increase?" → 30%. Formula: ((new − old) ÷ old) × 100
Add/remove a percentage — "Price before 20% VAT?" or "Price after 10% discount?" — useful for retail, tax, and finance

Percentage Increase vs. Decrease

Percentage change is directional. A positive result is an increase; a negative result is a decrease. Note that a 50% decrease followed by a 50% increase does not return to the original value — the increase is calculated on the lower base. For example: €100 − 50% = €50, then €50 + 50% = €75, not €100.

Real-World Applications

VAT calculations — add or remove VAT at the applicable local rate to find the net or gross figure
Discounts — calculate the sale price or the saving from a percentage-off offer
Pay rises — determine your new salary after a 3%, 5%, or 10% increase
Investment returns — express a gain or loss as a percentage of the original investment
Statistics and data — understand survey results, growth rates, and market share figures

Tips for Percentage Calculations

A useful mental shortcut: 10% of any number is simply the number divided by 10. From there, 5% is half of 10%, 20% is double 10%, and 1% is 10% divided by 10. Combining these makes many percentage calculations possible without a calculator.

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Important Note: This tool is intended to provide estimates and should not be used as a substitute for professional advice. Information generated by these calculators may be incomplete and does not account for all individual circumstances. Always seek the counsel of a certified expert (such as a financial advisor, healthcare provider, or licensed engineer) before taking action based on these results.

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% Percentage Calculator

What is X% of Y?

X is what % of Y?

Percentage Change (increase / decrease)

Add or Remove a Percentage