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Date calculator
Find the number of calendar days between dates.
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Percentage calculator
Calculate percentages, proportions and changes.
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Which value is the denominator for a percentage?
Use the whole for a proportion and the original value for percentage change. 50 out of 200 is 25%; moving from 200 to 250 is also a 25% increase, but these are different questions.
| Task | Inputs in order | Result |
|---|---|---|
| 15% of 200 | Base 200 / percentage 15 | 30 |
| 50 out of 200 | Whole 200 / part 50 | 25% |
| 200 → 250 | Original 200 / new 250 | 25% |
| 200 → 150 | Original 200 / new 150 | −25% |
A rate moving from 10% to 15% rises by 5 percentage points, or 50% relative to its original value. Change from zero is undefined. Inputs must be nonnegative; a decrease appears as a negative result.
Use the discount calculator for sale prices and savings.How to use
- Choose percentage of a number, part of a whole or percentage change.
- Enter the base first, then the percentage or comparison value.
- Calculate and read the result for your selected mode.
How it works
Percentage of a number = base × percent ÷ 100. Proportion = part ÷ whole × 100. Change = (new − original) ÷ original × 100.
Common questions
How are decreases shown?
A decrease has a negative sign. Going from 200 to 150 gives −25%.
Can the original value be zero?
Proportions and changes cannot use a zero denominator. Percentage of a number can use a zero base.
Is this percentage points?
No. Moving from 10% to 15% is 5 percentage points, but a relative increase of 50%.