Arithmetic
Percentage Calculator
Solve every common percentage scenario—find the part, the whole, the percentage itself, or the percent change between two values.
Switch between finding parts, wholes, raw percentages, or percentage change.
Core percentage relationships
part = whole × (percentage ÷ 100)
Depending on the selected mode the calculator rearranges the same relationship to isolate the unknown value. Percent change uses ((new − old) ÷ old) × 100.
How to use
- Choose the mode that matches your question (Part, Whole, Percent, or Change).
- Fill in the known values in the input fields that appear.
- Read the solved value in the results stack immediately below the inputs.
Example
Input: Mode = Part, Whole = 150, Percent = 20
Output: Part = 30
Student-friendly breakdown
This walkthrough emphasizes the most searched ideas for Percentage Calculator: percentage calculator, percent calculator, percentage change calculator, percentage decrease calculator. Start with the formula above, then follow the guided steps to double-check your work. For quick revision, highlight the givens, plug into the equation, and finish by verifying your units.
Need more support? Use the links below to open the long-form guide, browse additional examples, or hop into adjacent calculators within the same topic — each one is a quick way to double-check your work or handle a related question without starting from scratch.
Deep dive & study plan
Percentage Calculator: Find parts, originals, raw percent values, or percentage change. It's built around percent, change, whole, part, so you can go from a raw question to a checked answer without switching tools.
The math behind it: Depending on the selected mode the calculator rearranges the same relationship to isolate the unknown value. Percent change uses ((new − old) ÷ old) × 100. The core relationship is part = whole × (percentage ÷ 100), shown above the calculator so you can see exactly how your inputs turn into the result.
To use it well: (1) Choose the mode that matches your question (Part, Whole, Percent, or Change). (2) Fill in the known values in the input fields that appear. (3) Read the solved value in the results stack immediately below the inputs. Keep your units consistent as you go, and re-run a case you already know the answer to — it's the fastest way to catch a typo before it throws off a result you're relying on.
Worked example: entering Mode = Part, Whole = 150, Percent = 20 returns Part = 30. Try swapping in your own numbers next, especially a case you're unsure about, before you use this for something that matters.
Quick retention checklist
- Speak the formula aloud (or annotate it) so the relationships stick.
- Write each step in your own words and compare with the numbered list above.
- Swap in new numbers for the Example to make sure the calculator (and your logic) handles edge cases.
- Check at least one related calculator below — it's the fastest way to confirm your numbers still line up from a different angle.
FAQ & notes
Can I enter negative numbers?
Yes. Negative amounts work for change calculations and for scenarios such as refunds or debt reductions.
How is percent change different from percent of?
Percent change compares an old value to a new value and reports the relative difference, while percent of answers “X is what percent of Y.”
What formula does the Percentage Calculator use?
Depending on the selected mode the calculator rearranges the same relationship to isolate the unknown value. Percent change uses ((new − old) ÷ old) × 100.
How do I use the Percentage Calculator?
Choose the mode that matches your question (Part, Whole, Percent, or Change). Fill in the known values in the input fields that appear. Read the solved value in the results stack immediately below the inputs.