How this tool works
The Percentage Calculator applies standard percentage formulas according to the calculation mode selected by the user.
Basic percentage calculations divide the percentage by 100 and apply it to the provided number. Percentage change uses the original value as the baseline, while percentage difference compares two values against their average absolute magnitude.
Reverse-percentage calculations divide the final value by the applicable percentage multiplier rather than adding or subtracting the percentage directly.
Commerce modes use standard formulas for discounts, included and excluded taxes, tips, profit margins, and markups. Repeated percentage growth uses compound multiplication across the selected number of periods.
Results are calculated locally in the visitor’s browser and formatted with useful decimal precision.
Important assumptions
Entered values are assumed to be expressed in compatible units.
Percentage change assumes that the first entered value is the original baseline. Percentage difference treats both values equally and uses their average absolute magnitude as the comparison base.
Tax and GST calculations use the percentage rate manually entered by the user. The calculator does not determine which statutory rate applies to a product, service, transaction, or jurisdiction.
Profit margin uses revenue as the denominator, while markup uses cost as the denominator.
Repeated percentage growth assumes the same percentage change is applied during every period.
Limitations
The calculator performs mathematical percentage operations and does not provide financial, tax, accounting, legal, academic, or pricing advice.
Tax and GST modes do not determine tax eligibility, exemptions, classifications, filing obligations, or jurisdiction-specific rules.
Commercial calculations do not include transaction fees, currency conversion, rounding regulations, additional taxes, rebates, or other charges unless those values are incorporated manually.
Results involving repeating decimals may be rounded for display. Users should verify calculations independently when exact precision is required for regulated, contractual, academic, or financial purposes.
Frequently asked questions
What is the formula for calculating a percentage of a number?+
Multiply the number by the percentage and divide the result by 100. For example, 20% of 500 is calculated as 500 × 20 ÷ 100, giving a result of 100.
How is percentage change calculated?+
Subtract the original value from the new value, divide the difference by the absolute original value, and multiply by 100. A positive result indicates an increase and a negative result indicates a decrease.
What is the difference between percentage change and percentage difference?+
Percentage change uses one value as the original baseline. Percentage difference treats both values equally and divides their absolute difference by the average magnitude of the two values.
How do I reverse a percentage increase?+
Divide the final value by one plus the percentage expressed as a decimal. For example, if a value becomes 120 after a 20% increase, divide 120 by 1.20 to recover the original value of 100.
How do I find the original price before a discount?+
Divide the discounted price by one minus the discount rate expressed as a decimal. For example, if the sale price is 800 after a 20% discount, divide 800 by 0.80 to get the original price of 1,000.
Are profit margin and markup the same?+
No. Profit margin divides profit by revenue or selling price. Markup divides profit by cost. The same transaction therefore produces different margin and markup percentages.
Does PMNM store the numbers entered?+
The percentage calculations run locally in the browser. The values and generated results do not need to be submitted to WordPress. Recent calculation history is stored only in the current browser and can be cleared by the user.
Tool changelog
Released the first Percentage Calculator module with basic percentages, percentage change, percentage difference, increases and decreases, reverse percentages, discount, tax, tip splitting, profit margin, markup, percentage error, score percentage, ratio conversion, repeated growth, local history, formula explanations, and calculation steps.
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