Percentage calculator: four useful calculations
Choose the question you need to solve, enter two numbers and get both the answer and the calculation. The examples use plain numbers; apply a currency symbol or unit only when it fits your own context.
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Examples for each calculation
- 15% of 200 = 30. For a 200-unit bill, that is 30 units; the currency depends on your context.
- 36 out of 45 questions = 80%. Divide the part by the total, then multiply by 100.
- A value rising from 1,200 to 1,320 changes by +10%; a fall from 50 to 42 is −16%.
- If a value is 660 after a 10% increase, its original value was 600. Dividing 660 by 0.9 would reverse a 10% discount instead.
Frequently asked questions
Why does reversing a 10% increase not mean subtracting 10%?
Because the percentage is calculated from a different base. An increase from 600 by 10% gives 660, but subtracting 10% of 660 gives 594. To reverse a p% increase, divide the final value by 1 + p/100.
How do I combine two successive discounts?
Multiply the remaining-value factors. A 20% discount followed by 10% off the reduced price leaves 0.8 × 0.9 = 0.72 of the original price, so the total discount is 28%, not 30%.
Can a percentage be greater than 100%?
Yes. A 150% increase means adding one and a half times the starting value, for a final value 2.5 times as large. A part can also exceed a reference total, depending on what is being compared.
What is the difference between percentage points and percent?
A rate moving from 10% to 12% rises by 2 percentage points. Relative to its original 10% rate, that is a 20% increase. Use percentage points for the direct difference between two rates.
How do I calculate percentage change in a spreadsheet?
Use (new value − old value) ÷ old value and format the result as a percentage. The calculator uses the same formula; the starting value must not be zero.
Percentage and percentage points are different
If an interest rate changes from 10% to 12%, the difference is 2 percentage points, while the relative increase is 20%. The first compares the two rates directly; the second measures the change relative to the starting rate.
Successive changes multiply
A 10% increase followed by another 10% increase multiplies the starting value by 1.1 × 1.1 = 1.21, for a total increase of 21%. A later percentage uses the updated value as its base.
A quick mental-math shortcut
Ten percent is one tenth of a value, five percent is half of ten percent, and one percent is one hundredth. For example, 35% of 80 is 30% (24) plus 5% (4), or 28.
Related tools
For compound growth over time, use the compound-interest calculator (currently in Portuguese). Compound-interest calculator