Free Percentage Calculator

6 calculators in one — % of a number, % change, reverse %, and more

Calculate percentages instantly for discounts, markups, grades, growth rates, and financial analysis. Switch between 6 modes covering every common percentage calculation, with the formula shown for every result.

100% free

6 calculators in 1

No sign-up required

% of a Number

Find out what a given percentage of a number equals

What is % of ?

What % is X of Y

Find what percentage one number is of another

is what % of ?

% Increase / Decrease

Calculate the percentage change from an original value to a new value

Original Value New Value

% Difference

Compare two values with no baseline — uses their average

Value 1 Value 2

Add / Subtract Percentage

Add or remove a percentage from a number (e.g. tax, markup, discount)

Base Number Percentage Operation

Reverse Percentage

Find the original number before a percentage was applied

Final Value (after % applied) Percentage Applied Was this an increase or decrease?

Result

100

Common Percentage Formulas

Every calculation this tool performs, explained

Calculation	Formula	Example
% of a number	(Percent ÷ 100) × Number	20% of 500 = 100
What % is X of Y	(X ÷ Y) × 100	25 of 200 = 12.5%
% Increase/Decrease	((New − Old) ÷ Old) × 100	100 → 125 = +25%
% Difference	(\|V1 − V2\| ÷ average) × 100	80 & 120 = 40% diff
Add/Subtract %	Number × (1 ± Percent/100)	250 + 15% = 287.5
Reverse %	Final ÷ (1 ± Percent/100)	80 after 20% off → 100

Where This Calculator Is Useful

🛒 Discounts & Sales

Use "% of a Number" to find sale prices, or "Reverse %" to find the original price before a discount was applied — useful for verifying advertised savings.

📈 Business & Growth

Use "% Increase/Decrease" to track revenue growth, conversion rate changes, or year-over-year performance for your Shopify store.

💰 Tax & Markup

Use "Add/Subtract %" to quickly add sales tax to a price or calculate a markup on your cost price.

📊 Comparing Two Values

Use "% Difference" when comparing two independent numbers with no clear "before/after" relationship, like comparing two suppliers' prices.

🎓 Grades & Scores

Use "What % is X of Y" to calculate a test score, completion rate, or any ratio expressed as a percentage.

🧾 Tips & Splitting Bills

Use "% of a Number" to quickly calculate a tip amount on a bill total before splitting between guests.

Need Custom Pricing or Discount Logic Built Into Your Store?

Codify Infotech builds custom Shopify apps for dynamic pricing, tiered discounts, and markup automation

Get Free Consultation Shopify App Development

Frequently Asked Questions

Yes. Codify Infotech's Percentage Calculator is 100% free with no signup, no login, and unlimited calculations.

Divide the first number by the second number, then multiply by 100. For example, to find what percent 25 is of 200, divide 25 by 200 to get 0.125, then multiply by 100 to get 12.5%. Use the "What % is X of Y" tab to calculate this instantly.

Subtract the original value from the new value, divide by the original value, then multiply by 100. A positive result is a percentage increase and a negative result is a percentage decrease. Use the "% Increase/Decrease" tab to calculate this automatically.

Percentage change compares a new value to an original value, treating one as the baseline (used for growth, discounts, raises). Percentage difference compares two values with no baseline, dividing by their average — typically used when comparing two independent measurements rather than tracking a change over time.

Reverse percentage finds the original number before a percentage was applied. For example, if a discounted price of $80 reflects a 20% discount, the original price is calculated by dividing 80 by (1 − 0.20), which equals $100. Use the "Reverse %" tab to calculate this instantly.

No. All calculations run directly in your browser using JavaScript. No numbers you enter are sent to or stored on our servers.

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