Math Converters

Convert between percents, fractions, decimals, numeral systems and more.

Two families of conversion live here. The first changes how a value is written without changing the value: a percentage, a decimal and a fraction are three ways of writing the same ratio, so 0.25, 25% and 1/4 are interchangeable. The rules are short, multiply by 100 to go from decimal to percent and divide the numerator by the denominator to go from fraction to decimal, and the guides show the steps so you can repeat them by hand. Fraction to percent and percent to fraction are two of the most popular.

The second family changes the base of a whole number. Binary uses two digits, decimal ten and hexadecimal sixteen, which is why programmers group four binary digits into one hex digit: binary 1111 is hex F is decimal 15. There are converters for decimal to binary, binary to decimal, binary to hex, hex to binary, decimal to hex and hex to decimal. The Roman numerals converter works in both directions.

Popular math converters

• Percent to Fraction ConverterA percentage as a fraction in lowest terms.
• Fraction to Percent ConverterNumerator and denominator to a percentage, mixed numbers included.
• Roman Numerals ConverterWhole numbers to Roman numerals and back.
• Decimal to Binary ConverterDecimal to binary, with the division method shown.

All math converters

• Binary to Decimal ConverterType a binary number and its decimal value appears as you type. The guide below explains the place-value method so you can check any result by hand.
• Binary to Hex ConverterEnter a binary number and its hexadecimal form appears as you type. The guide shows the four-bit grouping trick that makes this conversion easy to do by hand.
• Decimal to Binary ConverterEnter a decimal number and its binary form appears as you type. The guide below walks through the division method so you can verify the answer yourself.
• Decimal to Fraction ConverterEnter a decimal number and the matching simple and mixed fractions appear as you type. The guide explains the method and how to get clean answers for repeating decimals.
• Decimal to Hex ConverterEnter a decimal number and its hexadecimal form appears as you type. The guide below explains the divide-by-16 method and the quirks of fractions and very large values.
• Decimal to Percent ConverterEnter a decimal number and the equivalent percentage appears as you type. The guide below explains the rule and what happens to long decimals.
• Fraction to Decimal ConverterEnter the numerator and denominator and the decimal value appears as you type. The guide below shows how to do the division by hand and when a decimal repeats.
• Fraction to Percent ConverterEnter the numerator and denominator and the percentage appears as you type. The guide below covers the formula, mixed numbers and what to expect from repeating values.
• Hex to Binary ConverterType a hexadecimal number and its binary form appears as you type. The guide below shows the simple digit-by-digit swap that does the same job on paper.
• Hex to Decimal ConverterType a hexadecimal number and its decimal value appears as you type. The guide below shows how to do the same sum by hand using powers of 16.
• Percent to Decimal ConverterType a percentage and the decimal equivalent appears straight away. The rule is simple: divide by 100, which moves the decimal point two places to the left.
• Percent to Fraction ConverterEnter a percentage and get the equivalent fraction in lowest terms, shown as a mixed number when the value is above 100%. The guide explains how to do the same conversion by hand.
• Roman Numerals ConverterType a whole number to see its Roman numeral, or type a Roman numeral such as MCMXCIV to see the number. The answer updates as you type.