Percentage calculator
Four common percentage calculations in one tool, with a visible calculation instead of a mysterious result.
Calculate a percentage value and rate
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First choose the quantity you need: percentage value, percentage rate, base value or change.
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Enter the two values you already know.
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The result and calculation appear as soon as both values have been entered.
If you need a bespoke version
You can keep using this free tool as it is. If you need a bespoke version with your own rules, data or workflows for a website, shop or internal process, I can build it for you – for example with custom rules and data sources, approvals and exports, and website or shop integration.
How this tool calculates
The percentage value is the base value multiplied by the percentage rate and divided by 100. For changes, the difference is divided by the original value.
Your inputs and results remain on your device. Reloading the page restores the default values.
Terms used in this calculation
- Base value
- The whole from which a percentage share is calculated.
- Percentage value
- The specific part of the base value.
- Percentage rate
- The share in hundredths, shown with the % sign.
Frequently asked questions
How do I calculate 19 per cent of 250?
Choose percentage value, enter 250 as the base value and 19 as the percentage rate.
Why does adding 20 per cent and then subtracting 20 per cent not return to the original value?
Because the second calculation uses a different base value. The change calculator shows this difference.