The formula this page uses
part = percent ÷ 100 × whole percent = part ÷ whole × 100 whole = part ÷ (percent ÷ 100)
Percent Calculator
Use the free percent calculator to work through the number relationship, preserve exact values, and check the result with estimation. Choose a focused operation below to calculate, inspect the method, and connect the result to a visual model.
The visual updates with your calculation.
Result—Choose a mode, enter the known values, and calculate.
Show your work Step-by-step method
- The calculation method and verification will appear here.
Arithmetic
Percent Calculator explained
The short version
- Percent means 'out of 100', so 18% is just another way of writing 18/100 or 0.18.
- Three questions hide in every percent problem: find the part, find the percent, or find the whole.
- Finding the whole is the one people get wrong, because you have to divide instead of multiply.
What each part means
SymbolWhat it means
percent — The rateThe number in front of the % sign. It is not a decimal until you divide it by 100.
whole — The starting amountWhat the percent is taken out of, in dollars, kilograms, marks or anything else.
part — The pieceThe answer when you want an amount. It carries the same unit as the whole.
100 — The scaling numberPercent is a fraction with 100 hidden on the bottom, and this is that 100.
Show your work: a full example
- The questionwhat is 18% of 45?
- Turn the percent into a decimal18 ÷ 100 = 0.18
- Multiply by the whole0.18 × 45 = 8.1
- Check by splitting the percent up10% of 45 = 4.5
- Work out the other 8%0.08 × 45 = 3.6
- Add the two pieces4.5 + 3.6 = 8.1
A second, different case
- A different case: the whole is missinga jacket costs 63 dollars after 30 percent off
- Work out what percent 63 dollars is100% − 30% = 70%
- Turn that into a decimal70 ÷ 100 = 0.70
- Divide instead of multiplying63 ÷ 0.70 = 90
- Check the discount0.30 × 90 = 27
- Check the sale price90 − 27 = 63 dollars, so the tag price was 90 dollars
Copy-ready example
what is 18% of 45?
The question
Questions about the Percent Calculator
What does the % sign actually stand for?
It is a squashed-up way of writing 'per 100'. The little circles are the two zeros of 100 and the slash is the division line. So 45% literally reads as 45 out of every 100.
How do I work out a 15 percent tip without a calculator?
Find 10 percent by moving the point one place left, then add half of that. On a bill of 46 dollars, 10 percent is 4 dollars 60 cents and half of that is 2 dollars 30 cents, so the tip is 6 dollars 90 cents.
Can a percent be more than 100?
Yes, whenever the part is bigger than the whole. If a shop sold 50 tickets last week and 60 this week, this week is 120 percent of last week: 1.20 × 50 = 60. Anything above 100 percent simply means more than the original amount.
What is the difference between 30 percent of and 30 percent off?
'30 percent of 90' asks for the piece, which is 27. '30 percent off 90' asks for what is left, which is 90 − 27 = 63. The same multiplication does both, but 'off' needs the extra subtraction.
Calculate, interpret, verify.
This workspace keeps the formula and the meaning together. Decimal results are rounded for display; retain full precision when you continue a calculation.
Enter known values
Match each input to the quantities in the problem and keep units consistent.
Use the relationship
The result panel identifies the formula or algorithm and shows the main substitutions.
Read the visual
Use the diagram, plot, or data display to check scale, direction, and plausibility.
Practice unaided
Move to targeted questions once you can explain why the method applies.
A calculator gives you the number. If you also want to be able to do this without one, understanding percentages walks through the method step by step, with a worked example and the mistakes that cost marks.
Learn the mathematics
Understand arithmetic behind this calculator
A calculator confirms an answer. Working the method yourself is what makes the next problem faster.