Formula and method
This calculator uses the values you enter and applies the calculation immediately in your browser. The main output formulas are:
- Percentage change:
((newValue-original)/original)*100
Some formulas are undefined for certain input combinations, such as division by zero, equal x-values in a slope calculation, or logarithms of non-positive numbers. In those cases the live tool reports that the result is undefined instead of displaying Infinity or NaN.
Examples
- Example: with Original value = 80, New value = 100, this calculator returns Percentage change = 25 %.
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- Try related education & math tools when your next step needs another conversion or calculation.
The mistake that trips up percentage change math
Percentage increase and percentage of the new total are two different numbers people often confuse. Going from 50 to 75 is a 50% increase (the change, 25, is 50% of the original 50) -- but 75 is not '50% more than 50' in the sense of being 150 relative to some other baseline; it's exactly that increase relative to the starting value. When reversing a percentage increase to find the original number, remember that a 20% increase followed by a 20% decrease does not return you to the original value -- the decrease is calculated on a larger number.
Embed this tool
Paste this snippet into your own site or blog post to embed a live, working copy of this tool. It links back to the full page on SpecWhale.
Frequently asked questions
Is Percentage Increase/Decrease Calculator free to use?
Yes. Percentage Increase/Decrease Calculator is completely free, has no usage limit, and does not require an account, email, or API key.
Does Percentage Increase/Decrease Calculator store or upload my data?
No. Percentage Increase/Decrease Calculator calculates everything locally in your browser. Nothing you type is sent to a server or stored by SpecWhale.
How accurate is Percentage Increase/Decrease Calculator?
Percentage Increase/Decrease Calculator uses a standard formula (see the Method section above for the exact expression). For high-stakes financial, medical, or legal decisions, confirm the result with a professional or an authoritative source before relying on it.
Can I embed Percentage Increase/Decrease Calculator on my own website?
Yes. Use the "Embed this tool" snippet on this page to add a free, working copy of Percentage Increase/Decrease Calculator to your own blog post or page.
SEO and sharing notes
This page has a single clean canonical URL, descriptive metadata, breadcrumb structured data, and internal links to related tools. Supported calculators and converters can also copy a prefilled share link without changing the canonical index URL.