Percentage Calculator
Calculate a percentage of a value, compare a part and whole, or find percentage change between two values.
Calculate common percentages
Choose whether to find a percentage of a value, find what percentage one value is of another, or calculate percentage change. Percentage change uses the absolute starting value as its denominator; decreases therefore appear as negative results.
Enter your details
Change the values, then run the tool.
Data handling
- Processing
- The selected input is processed in your browser. Got A Tool does not send it to our servers.
- Retention
- We do not retain selected files. Resetting or closing this page clears its working state.
- Export
- The tool may prepare a result after you run it. It downloads or copies it only when you choose that action.
Advertising and analytics are separate site services. We do not send selected file contents to them. Read the Privacy Policy for details.
How it works
Percentage Calculator: a practical guide
Percentage calculations are useful for comparing quantities, finding a portion of a total, or describing a change between two values. This page covers three common formulas: X percent of Y, X as a percentage of Y, and percentage change from an initial value to a new value.
- STEP 01
Choose the percentage calculation that matches your question.
- STEP 02
Enter the two values in the labeled fields.
- STEP 03
Calculate and review the result, including whether a change is an increase or decrease.
What this tool does and its limits
For percentage change, the calculation is (new value − starting value) divided by the absolute starting value, multiplied by 100. A zero starting value has no defined percentage change and is rejected. A zero comparison value is also rejected when finding what percent one number is of another. Results are rounded for display, while the calculation uses JavaScript number arithmetic.
Processing happens in your browser. The selected file or entered values are not uploaded to Got A Tool or saved by this tool.
Frequently asked questions
- How do I find 20% of 150?
- Choose “What is X% of Y?”, enter 20 and 150, and calculate. The result is 30.
- How is percentage change calculated?
- Subtract the starting value from the new value, divide by the absolute starting value, then multiply by 100. A negative result is a decrease.
- Why can't the starting value be zero?
- Percentage change divides by the starting value, so a zero baseline makes the result undefined.
- Does this handle currency or units?
- It calculates numeric values only. Add the currency or unit label yourself when interpreting the result.
Keep working
Related tools
Bulk UTM Link Builder
Create campaign URLs from a CSV, report invalid rows, and download only valid links.
Open tool →SKU Pick List Generator
Aggregate order quantities by SKU, sort by bin, and print one pick list.
Open tool →Word & Character Counter
Count words, Unicode characters, sentences, paragraphs, lines, bytes, and estimated reading time locally.
Open tool →