Percent Solver
Type one percent equation. Use ? or what for the missing value.
One supported equation at a time; nothing is sent to a server.
- Formula
- Check
Guided percentage calculator
Batch percent solver · up to 100 lines
Three percent equations, one missing value
The basic relationship is part = (percent ÷ 100) × whole. If you know any two values, rearrange the same equation to find the third. This page recognizes explicit forms such as 15% of 240, 18 is ?% of 60, and 18 is 30% of ?.
| Find | Formula | Example |
|---|---|---|
| Part | (percent ÷ 100) × whole | 15% of 240 = 36 |
| Percent | part ÷ whole × 100 | 18 is ?% of 60 → 30% |
| Whole | part ÷ (percent ÷ 100) | 18 is 30% of ? → 60 |
Percent change and percentage-point difference
For a positive starting value, percent change = (new − original) ÷ original × 100. Enter 80 to 100 to calculate a 25% increase. If the original is negative, this tool instead labels the result as signed change relative to |original|; it is not presented as standard percent change. A warning also appears if the comparison crosses zero.
When both entries are percentages, the direct subtraction is measured in percentage points. Moving from 20% to 30% is +10 percentage points, but the relative change is +50%. The solver displays both instead of treating those statements as interchangeable.
Zero, rounding, and supported input
A zero denominator does not produce a made-up result. For example, percent change from 0 is undefined; a nonzero part cannot be a percentage of a zero whole; and 0 is 0% of any whole, so that equation has infinitely many answers.
Inputs may contain decimals, negative numbers, correctly grouped thousands, and percentages above 100. The parser intentionally accepts only the shown formats—it does not guess at unsupported prose, currency, or measurement units. Decimal-place controls change displayed text only; calculations use the unrounded value.
Batch percent calculations
Open batch mode to process up to 100 non-empty lines. Each line may use a different supported equation. Blank lines are ignored, while an invalid line blocks the copyable output and identifies its original line number.
Frequently asked questions
How do I calculate to find a percentage?
Divide the part by the whole, then multiply by 100. For example, 18 divided by 60 is 0.3, so 18 is 30% of 60.
How much is 20% out of 70?
Convert 20% to 0.2 and multiply by 70. The result is 14. Enter 20% of 70 to see the substitution and check.
How do I calculate the percentage of an amount?
Divide the percentage by 100, then multiply it by the whole amount. The solver accepts percentages above 100 and negative values in part, percent, or whole equations. A change from a negative original is labeled separately as signed change relative to its absolute original.
What is the difference between percent change and percentage points?
For a positive original, percent change compares the change with that starting value. Percentage points are the direct difference between two percentages. Moving from 20% to 30% is a 50% relative increase and a 10-percentage-point increase. A negative original is labeled as signed change relative to |original|, not standard percent change.
Why is percent change undefined when the starting value is zero?
The percent-change formula divides by the starting value. Division by zero is undefined, so the solver reports that state instead of showing Infinity or a misleading percentage.
Can I solve several percent questions at once?
Yes. Batch mode accepts up to 100 non-empty lines in the supported formats. If one line is invalid, it reports the original line number and disables the batch copy.