Percentage Calculator
Work out any everyday percent problem in seconds with this free percentage calculator. Find what X percent of a number is, see what share one number is of another, measure percent change, or add and subtract a percent. Students use it for grades, shoppers check sales, and small businesses do quick price math. Everything runs in your browser, so your numbers never leave your device. You can also work backwards: if 65 is 26% of a number, the “Y is P% of what?” tab finds the whole, which is 250.
Percent formulas in plain words
X percent of Y = (X ÷ 100) × Y. X as a percent of Y = (X ÷ Y) × 100. Percent change = ((New − Old) ÷ Old) × 100. To add X percent to Y: Y × (1 + X/100). To subtract X percent from Y: Y × (1 − X/100). Y is P percent of what = Y ÷ (P ÷ 100).
Solved example: a price rise from $40 to $50
A jacket costs $40 in spring and $50 in fall. Here is the percent increase, step by step. Step 1: find the difference, 50 − 40 = 10. Step 2: divide by the starting price, 10 ÷ 40 = 0.25. Step 3: multiply by 100, 0.25 × 100 = 25. The price rose by 25%.
How to use this calculator
- Pick the tab that matches your question — for example, “Percent change” for a price rise.
- Type your two numbers into the labeled boxes.
- Press Calculate and read the answer with the working shown underneath.
What this tool does not do
This is a general percent calculator, not financial advice. It does not compound growth over time, add sales tax, or convert currencies. Answers round to four decimal places — plenty for everyday math, but not precise enough for lab work.
Finding a percent of a number
This is the most common percentage problem there is: discounts, tips, tax and test scores all start here. The method is to turn the percent into a decimal by dividing by 100, then multiply. To find 15% of 240: 15 ÷ 100 = 0.15, and 0.15 × 240 = 36. So 15% of 240 is 36.
There is a useful mental shortcut for round percents. Find 10% by dividing by 10, halve that for 5%, and add the pieces. For 15% of 240: 10% is 24, 5% is 12, and 24 + 12 = 36. The “X% of Y” tab above does the same thing instantly when the numbers are less friendly.
Finding what percent one number is of another
When you know the part and the whole and want the percent, divide the part by the whole and multiply by 100. If you scored 45 out of 60 on a test, that is 45 ÷ 60 = 0.75, and 0.75 × 100 = 75%. Your score is 75%. The same method answers everyday questions like “what percent of my battery is left?” (charge remaining ÷ full charge) or “what share of the bill did I pay?”
Percentage increase and decrease
Percent change always compares the change with the starting value — never with the new one. The formula is ((New − Old) ÷ Old) × 100. The solved example above shows a 25% increase, from $40 to $50. A decrease works identically: if the same jacket drops from $80 to $64, the change is 64 − 80 = −16, and −16 ÷ 80 = −0.2, a 20% decrease. Watch out for the trap: a fall from $80 to $64 is 20%, but climbing back from $64 to $80 is a 25% increase, because the starting value changed. For sale prices worked out in one step, the Discount Calculator is built for exactly that.
Adding and subtracting a percent
Adding a percent is how tax, tips and markups are worked out; subtracting one is how discounts are calculated. To add 8% tax to $120, multiply by 1.08: 120 × 1.08 = $129.60. To take 20% off $75, multiply by 0.80: 75 × 0.80 = $60. The multiplier is always 1 plus the percent for adding, or 1 minus the percent for subtracting.
One warning that catches people out: percents do not cancel. If $100 goes up 20% it becomes $120, but if it then falls 20%, the fall is 20% of $120, which is $24, leaving $96 — not $100. The “Add X%” and “Subtract X%” tabs above apply the multiplier method for you.
Working backwards: finding the whole
Sometimes you know the part and the percent and need the original whole. Divide the part by the percent (as a decimal). If 65 is 26% of a number, the number is 65 ÷ 0.26 = 250. This is the trick behind a common shopping puzzle: a jacket sells for $45 after 25% off, so $45 is 75% of the original price, and 45 ÷ 0.75 = $60 was the price before the sale. The “Y is P% of what?” tab does this in one step.
Common percentages as fractions and decimals
Every percent is a fraction out of 100, and the common ones simplify into fractions worth recognising. Spotting them makes estimates quick: 25% off is the same as paying 3/4, and a 12.5% tip is 1/8 of the bill.
| Percent | Fraction | Decimal |
|---|---|---|
| 1% | 1/100 | 0.01 |
| 5% | 1/20 | 0.05 |
| 10% | 1/10 | 0.1 |
| 12.5% | 1/8 | 0.125 |
| 20% | 1/5 | 0.2 |
| 25% | 1/4 | 0.25 |
| 33⅓% | 1/3 | 0.333… |
| 50% | 1/2 | 0.5 |
| 66⅔% | 2/3 | 0.667… |
| 75% | 3/4 | 0.75 |
| 90% | 9/10 | 0.9 |
To convert any other fraction into a percent, or to add, subtract, multiply and divide fractions themselves, use the Fraction Calculator.
Converting between percents, decimals and fractions
The three forms are one value wearing different clothes, and converting is quick. To turn a percent into a decimal, divide by 100 (or move the point two places left): 45% = 0.45, and 7% = 0.07. To turn a decimal into a percent, do the reverse: 0.6 = 60%. To write a percent as a fraction, put it over 100 and simplify: 45% = 45/100 = 9/20. And to turn a fraction into a percent, divide and multiply by 100: 3/8 = 0.375 = 37.5%. The tabs above and the table of common values cover most everyday cases.
Percentages in everyday life
Once you start noticing them, percents are everywhere. School grades are percents of the marks available. Shops combine them: a 30% discount and then tax on the reduced price, which is why the order of the two calculations matters. Restaurant bills add a tip percent and sometimes a tax percent to the same base. News reports quote unemployment rates, interest rates and election shares, nearly always as percents — and the difference between a percent change and a percentage-point change decides whether a headline is accurate. Even your phone speaks in percents when it tells you the battery is at 82%. The six tabs above were chosen because they cover almost all of these situations.
Common percentage mistakes
Adding percents directly. A 10% discount followed by another 20% off is not 30% off. The second discount applies to the already-reduced price: $100 becomes $90, then $72 — a total saving of 28%, not 30%.
Using the new value as the base. Percent change is always divided by the starting (old) value. Dividing by the new value is the most common reason percent-change answers come out wrong.
Confusing percent with percentage points. When a rate itself moves — say an interest rate from 4% to 5% — that is a rise of 1 percentage point, but a 25% relative increase. The FAQ below explains the difference in full.
Frequently asked questions
How do I use this page as a percentage increase calculator?
Open the “Percent change” tab, type the old value first and the new value second, then press Calculate. A positive answer is an increase; a negative one is a decrease.
What is the difference between a percent and a percentage point?
A percent is relative; a percentage point is absolute. If a rate moves from 10% to 15%, that is a 5-percentage-point move but a 50% increase.
Can a percentage be more than 100%?
Yes. 150% of 200 is 300. Percentages above 100% simply mean “more than the whole,” which is common for growth and markups.
Why does my answer show decimals?
Some results cannot be written as whole numbers. The tool rounds to four decimal places; for money, round the final answer to two.
Related tools
- Browse all CalcNova calculators
- Discount Calculator – work out sale prices and savings from any percent-off deal.
- Tip Calculator – split restaurant bills with tip in one step.