Convert Percent Fraction Decimal

This calculator converts between percentages, fractions, and decimals. Enter any one value—a percent like 37.5%, a fraction like 3/8, or a decimal like 0.375—and you get the other two forms instantly, with the fraction shown in simplest terms.

Formula

The core relationships are:

• Percent to decimal: divide by 100. decimal = percent / 100
• Decimal to percent: multiply by 100. percent = decimal × 100
• Percent to fraction: write the percent over 100, then simplify. fraction = percent / 100
• Fraction to percent: divide numerator by denominator, then multiply by 100. percent = (numerator / denominator) × 100
• Fraction to decimal: divide numerator by denominator. decimal = numerator / denominator

All variables are unitless numbers. The percent symbol (%) means “per hundred,� so 45% literally means 45 per 100, or 45/100.

Worked Example

Using the default values from the calculator:

1. Start with percent = 37.5%.
2. Convert to decimal: 37.5 ÷ 100 = 0.375.
3. Convert to fraction: 37.5/100 = 375/1000. Simplify by dividing numerator and denominator by 125: (375÷125)/(1000÷125) = 3/8.
4. Check with the fraction: 3 ÷ 8 = 0.375, and 0.375 × 100 = 37.5%. ✓

The calculator shows the same result: percent 37.5%, fraction 3/8, decimal 0.375.

Why These Conversions Matter

Percent, fraction, and decimal are three ways to say the same thing—a part of a whole. Percent is the most common in everyday life: sales discounts, interest rates, poll results, and exam scores all use it. Fractions appear in cooking (½ cup), construction (¾ inch), and math itself. Decimals are used in money ($0.99), measurements (2.5 km), and most scientific calculations.

Being fluent between them lets you compare values quickly. For example, is 3/8 bigger than 35%? Convert 3/8 to 37.5%, and you know immediately it’s larger. Without conversion, comparing a fraction to a percent is guesswork.

How to Convert: Step-by-Step for Each Direction

• Percent → Decimal: Drop the % sign and move the decimal point two places left. 25% → 0.25; 8% → 0.08; 150% → 1.50.
• Decimal → Percent: Move the decimal point two places right and add the % sign. 0.375 → 37.5%; 0.04 → 4%; 2 → 200%.
• Fraction → Decimal: Divide the top number by the bottom number. 1/4 = 1 ÷ 4 = 0.25. Some fractions repeat: 1/3 = 0.333…, so you round or use a bar.
• Decimal → Fraction: Write the decimal over 1, multiply top and bottom by 10 until the decimal is gone, then simplify. 0.75 → 75/100 → 3/4.
• Fraction → Percent: Do the division, then multiply by 100. 5/8 = 0.625 → 62.5%.
• Percent → Fraction: Put the percent over 100 and simplify. 20% → 20/100 → 1/5. For percents with decimals (like 37.5%), first multiply by 10 to clear the decimal: 37.5/100 = 375/1000 = 3/8.

Common Mistakes and How to Avoid Them

The most frequent error is mixing up the direction of the decimal shift. Remember: percent means “per hundred,� so going from percent to decimal you divide by 100 (move left). Going to percent you multiply by 100 (move right).

Another trap is forgetting to simplify fractions. The calculator does this automatically, but if you’re working by hand, always check that the numerator and denominator have no common factor other than 1. For example, 40/100 simplifies to 2/5, not 40/100.

Rounding is also a common source of error. When a fraction like 1/3 becomes 0.333…, rounding to 0.33 loses accuracy. If you need exactness, keep the fraction or use enough decimal places. For percent, 1/3 is exactly 33.333…%, but many people round to 33.3%—fine for casual use, but not for precise calculations.

Finally, watch out for percents greater than 100%. 200% equals 2, not 0.2. Percent can exceed 100 when the part is bigger than the whole, like a 150% price increase.

Real-World Examples

• Shopping: A shirt is 25% off. The discount as a decimal is 0.25, so you pay 0.75 of the price. If the shirt is $20, you pay $15.
• Cooking: A recipe calls for 2/3 cup of flour. To double it, you need 4/3 cups, which is 1.33 cups—or 133% of the original amount.
• Grades: You got 18 out of 20 on a test. That’s 18/20 = 0.9 = 90%.
• Finance: An interest rate of 3.5% as a decimal is 0.035. If you have $1,000, the yearly interest is $35.

Limits of the Calculator

This calculator handles simple conversions between the three forms. It does not handle mixed numbers (like 2 1/2) directly—you’d need to convert to an improper fraction first (5/2). It also doesn’t handle repeating decimals perfectly; if you enter 0.333, it treats it as exactly 333/1000, not 1/3. For exact work with repeating decimals, use the fraction form or a calculator that supports them.

Also note that the fraction input expects a slash format (numerator/denominator). If you enter a decimal fraction like 0.5/2, it won’t work—convert to a whole-number fraction first.

Frequently Asked Questions

How do I convert 0.125 to a percent?

Multiply by 100 and add the % sign: 0.125 × 100 = 12.5%. So 0.125 is 12.5%.

What is 3/4 as a percent?

Divide 3 by 4 to get 0.75, then multiply by 100 to get 75%. So 3/4 = 75%.

Why does percent mean “per hundred�?

The word “percent� comes from the Latin per centum, meaning “by the hundred.� So 50% means 50 out of every 100, which is why you divide by 100 to get the decimal.

Can a percent be more than 100?

Yes. If something grows by 150%, it means the increase is 1.5 times the original. For example, if a population doubles, it increases by 100%—the new amount is 200% of the old.

How do I convert a fraction like 5/8 to a decimal without a calculator?

Do long division: 5 ÷ 8 = 0.625. You can also think of it as 5/8 = 0.5 + 0.125 = 0.625, since 1/8 = 0.125.

What if my percent has a decimal, like 12.5%?

Treat it the same way: 12.5% = 0.125. For a fraction, 12.5/100 = 125/1000 = 1/8. The decimal point just means you have a fractional part of a percent.

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in p | Percent | % | 37.5 | 0
in f | Fraction (numerator/denominator) | - | 3/8 | 0
in d | Decimal | - | 0.375 | 0
out percent | Percent | % | (f_num / f_den) * 100 | 2
out fraction | Fraction | - | p / 100 | 2
out decimal | Decimal | - | p / 100 | 4