Percentage calculator with steps
Find a percent of a number, what percent one number is of another, the whole, or a percent change, with every step shown.
🧒 Kids: pick what you want to find, type two numbers and read the steps. Then try one on paper!
Percent calculator
What the calculator shows
Every answer comes with the steps a teacher would want to see, and a bar that shows the percent as part of a whole. Use it to check homework, not to replace it. Ask your child to solve the problem first, then compare their working line by line.
Most percent mistakes are not in the arithmetic. They come from choosing the wrong numbers to divide, and the steps make that choice clear every time.
Ready-made examples to try
Each link opens the calculator with the problem filled in.
- 20% of 80: A benchmark percent
- 15% of 60: 10% plus 5%
- 12.5% of 48: A percent with a decimal
- 12 is what % of 48?: Part ÷ whole × 100
- 7 is what % of 20?: A test score
- 18 is 30% of what?: Find 1%, then 100%
- From 40 to 50: A percent increase
- From 80 to 60: A percent decrease
How to solve the three percent questions
Almost every percent problem is one of three questions about a part, a whole and a percent. Knowing which one you are asked is half the work.
- Find the part: “What is 15% of 60?” Multiply the whole by the percent as a decimal: 60 × 0.15 = 9. See percent of a number.
- Find the percent: “9 is what percent of 60?” Divide the part by the whole: 9 ÷ 60 = 0.15 = 15%. See finding the percent.
- Find the whole: “9 is 15% of what?” Divide the part by the percent as a decimal: 9 ÷ 0.15 = 60.
How percent change works
Percent change compares a change with where you started. Find the change, divide by the starting amount, and multiply by 100. A price that goes from $40 to $50 has risen by $10, and 10 ÷ 40 = 25%.
The starting amount matters. Going back from $50 to $40 is a 20% decrease, not 25%, because the change is now divided by 50. See percent change.
Check with mental maths
A quick estimate catches most slips. For example, 10% of a number is one tenth of it, so 10% of 60 is 6. Then 5% is half of that, and 20% is double. If the calculator says 15% of 60 is 9, then 6 + 3 = 9 agrees.
Common percent mistakes the steps catch
- Dividing the wrong way: 48 ÷ 12 instead of 12 ÷ 48. The steps always divide the part by the whole.
- Forgetting to × 100: giving 0.25 when the question asks for a percent.
- Using the new amount in percent change. The steps divide by the starting amount.
- Treating 15% as 15: 15% of 60 is 9, not 900.
Percent skills by grade
| Grade | What children calculate | Standard |
|---|---|---|
| Grade 6 | Percent as a rate per 100; percent of a quantity; finding the whole | 6.RP.A.3c |
| Grade 7 | Percent increase and decrease, discounts, tax, tips, interest, markup, commission and percent error | 7.RP.A.3 |
In India, percentages start in class 7 and grow in class 8 with profit and loss, discount and simple interest.
For teachers
Project the calculator and ask the class to say which of the three questions is being asked before you type it. To set homework checks, share a link with the problem filled in, like ?mode=what&a=12&b=48. The mode can be of, what, whole or change. Nothing is stored and no login is needed.
More percentage help
- Percent practice: 10 questions on any of 11 skills, marked as you go.
- Percent calculator with steps: percent of a number, what percent, the whole and percent change.
- Fraction, decimal and percent converter with a hundred grid.
- Lessons: percent of a number · finding the percent · percent change · percent to decimal
- Worksheets: percent of a number · finding the percent · percent change · percent to decimal · make a percent test
Back to percentages for kids · decimals · fractions · 6th grade math · 7th grade math
Last reviewed
Questions parents ask
How do I use the percent calculator?
Choose what you want to find: a percent of a number, what percent one number is of another, the whole, or the percent change. Type the two numbers and the answer appears with every step.
How do you find a percent of a number?
Change the percent to a decimal by dividing by 100, then multiply. For example, 15% of 60 = 0.15 × 60 = 9.
How do you work out what percent one number is of another?
Divide the part by the whole, then multiply by 100. For example, 12 is 12 ÷ 48 = 0.25 of 48, which is 25%.
How do you find the whole from a percent?
Find 1% first, then 100%. If 18 is 30% of a number, 1% is 18 ÷ 30 = 0.6, so 100% is 60.
How do you calculate percent change?
Find the change, divide it by the starting amount and multiply by 100. From 40 to 50 is a change of 10, and 10 ÷ 40 = 0.25, so a 25% increase.
Is it OK for my child to use a percent calculator?
Yes, for checking. Ask your child to work the problem on paper first, then compare each step with the calculator’s.