Name the question and base
Decide whether direction matters and which value represents the whole or original.
Six exact percentage questions
Choose the right percentage formula before touching the numbers.
PercentCalc separates six calculations that are often confused: percentage of a number, part as percentage, directional change, adding or subtracting a rate, recovering the original, and symmetric difference. Exact rational arithmetic keeps the formula auditable; inputs and results stay on the page.
No account, upload, saved history, or generated result URL.
Three visible checks
Choose, calculate, verify
Keep exact decimal arithmetic
PercentCalc reduces rational values and rounds only the displayed result.
Read the formula, not only the answer
The visible substitution exposes a swapped value or wrong base before you use the result.
Six focused intents
Use the calculation that matches your question
- Find X% of a number.
- Express a part as a percentage of the whole.
- Measure an increase or decrease from the original.
- Add or subtract a percentage with one multiplier.
- Recover the value before a known change.
- Compare two peer values symmetrically.
Try the exact calculator
Use your own two values
Choose the question first, keep the base visible, and inspect the formula before using the result.