Every decimal conversion in one place — arithmetic, time, fractions, percentages and binary, all with step-by-step working.
Decimal calculators convert between decimals and the other ways we write numbers — fractions, percentages, hours and minutes, and binary. Every tool below shows the full working, uses exact arithmetic instead of rounded floating-point maths, and marks repeating results honestly. Pick the conversion you need from the cards, or use the comparison table further down.
Core decimal arithmetic and time conversions used in payroll, timesheets and everyday maths.
Add, subtract, multiply and divide decimals exactly, with optional rounding and full working. Avoids the usual floating-point errors.
0.1 + 0.2 = 0.3 TimeTurn hours and minutes, or a shift's start and end times, into decimal hours for payroll and invoices. Handles breaks and overnight shifts.
7 h 30 min = 7.5 TimeConvert decimal hours back into hours, minutes and seconds for rosters and payslips. Supports values over 24 hours and negatives.
7.5 = 7 h 30 minMove between decimals and fractions, including repeating decimals, mixed numbers and improper fractions.
Convert terminating or repeating decimals into simplified fractions, with the greatest common factor shown and mixed-number output.
0.625 = 5/8 FractionsDivide any fraction, improper fraction or mixed number into its exact decimal, marking repeating digits with an overline.
1/3 = 0.3̅ FractionsAdd, subtract, multiply and divide mixed numbers, and convert between mixed numbers and improper fractions.
1½ + 2⅓ = 3⅚Switch between decimals, fractions and percentages — including values above 100%, below 1% and negatives.
Multiply any decimal by 100 to get a percentage, with a fraction equivalent and a note on whether it sits above or below 100%.
0.625 = 62.5% PercentDivide a percentage by 100 to get its decimal. The % sign is optional, and small values like 0.5% are handled correctly.
62.5% = 0.625 PercentConvert proper, improper, mixed or negative fractions into percentages, with simplification and a rounding control for repeating results.
5/8 = 62.5% PercentTurn any percentage into a simplified fraction or mixed number, including decimal percentages and values above 100%.
62.5% = 5/8Convert between base 10 and base 2 for programming, networking and computer-science study.
Convert whole numbers, fractions and negatives into binary using repeated division and doubling, with every step listed.
10.5 = 1010.1 BinaryRead any binary number — including binary fractions — back into decimal using place values, with the full expansion shown.
1010 = 10Other tools from the Math Hub that pair naturally with decimal work.
Add, subtract, multiply and divide fractions, with automatic simplification of the answer.
Work out percentages, percentage change and "what percent of" questions in one place.
Simplify ratios, scale them up or down, and solve for a missing term.
Find the greatest common factor — the step that simplifies any fraction to its lowest terms.
Find the lowest common multiple, used when adding fractions with different denominators.
What each calculator takes in, what it gives back, and a typical example:
| Calculator | Input | Output | Example |
|---|---|---|---|
| Decimal Calculator | Two or more decimals | Exact sum, difference, product or quotient | 0.1 + 0.2 = 0.3 |
| Time to Decimal | Hours & minutes, or start & end time | Decimal hours | 7 h 30 min = 7.5 |
| Decimal to Time | Decimal hours | Hours, minutes, seconds | 7.5 = 7 h 30 min |
| Decimal to Fraction | Terminating or repeating decimal | Simplified fraction, mixed number | 0.625 = 5/8 |
| Fraction to Decimal | Fraction or mixed number | Exact decimal, repeating marked | 1/3 = 0.3̅ |
| Decimal to Percent | Decimal | Percentage | 0.625 = 62.5% |
| Percent to Decimal | Percentage | Decimal | 62.5% = 0.625 |
| Fraction to Percent | Fraction or mixed number | Percentage | 5/8 = 62.5% |
| Percent to Fraction | Percentage | Simplified fraction, mixed number | 62.5% = 5/8 |
| Mixed Number | Two mixed numbers | Sum, difference, product or quotient | 1½ + 2⅓ = 3⅚ |
| Decimal to Binary | Decimal (base 10) | Binary (base 2) | 10.5 = 1010.1 |
| Binary to Decimal | Binary (base 2) | Decimal (base 10) | 1010 = 10 |
Start from what you already have, then pick the matching tool:
Decimals. A decimal writes a number using place values that are powers of ten. The digits after the point are tenths, hundredths, thousandths and so on, which is why moving the point one place multiplies or divides by 10.
Fractions. A fraction is a division waiting to happen: the line means "divide". Every terminating and every repeating decimal can be written as a fraction, which makes them rational numbers. After simplifying, a fraction only produces a decimal that ends when its denominator has no prime factors other than 2 and 5.
Percentages. Percent means "per hundred", so a percentage is just a fraction with 100 on the bottom. That is why converting a decimal to a percent multiplies by 100, and going back divides by 100. Percentages above 100% are perfectly valid — they simply mean more than one whole.
Binary numbers. Binary is base 2, using only the digits 0 and 1, with place values of 1, 2, 4, 8, 16 and so on. Computers use it because each digit maps to a simple on/off state. Some decimal fractions, such as 0.1, repeat forever in binary — which is exactly why ordinary computer arithmetic can produce small rounding errors.
If you are learning these conversions rather than just checking an answer, work through them in pairs. Convert 5/8 to a decimal, then convert 0.625 back to a fraction and confirm you land where you started. Doing the round trip catches misunderstandings that a single conversion can hide.
The most useful thing to memorise is the small set of everyday equivalents — 1/2 = 0.5 = 50%, 1/4 = 0.25 = 25%, 1/5 = 0.2 = 20%, 1/8 = 0.125 = 12.5%. Once those are automatic, most other conversions can be estimated in your head and checked with a calculator.
What is a decimal calculator?
A decimal calculator works with numbers written in decimal form. On this page the term also covers converters that change decimals into fractions, percentages, hours and minutes, or binary.
Which calculator converts a decimal to a fraction?
Use the Decimal to Fraction Calculator. It handles decimals that end, such as 0.625 = 5/8, and repeating decimals such as 0.333… = 1/3.
Which calculator converts a fraction to a percentage?
Use the Fraction to Percent Calculator. It simplifies the fraction first, then divides and multiplies by 100, so 5/8 becomes 62.5%.
How do I convert a timesheet to decimal hours?
Use the Time to Decimal Calculator. It converts hours and minutes, or a shift's start and end times, into decimal hours and can deduct an unpaid break.
Are these calculators free to use?
Yes. Every calculator on this page is free with no sign-up, works on any device, and runs in your browser so your entries stay private.
Do the calculators show the working?
Yes. Each one lists the steps behind the answer, which makes them useful for learning and for checking schoolwork rather than only getting a result.
Do they handle repeating decimals?
Yes. Repeating results are detected exactly and marked with a bar over the repeating digits. When a value has to be rounded, it is clearly labelled as rounded rather than shown as exact.
Can they handle negative numbers?
Yes. The conversion calculators accept negative values and keep the sign in the result, so -0.2 becomes -20% and -3/5 becomes -60%.
Why do computers struggle with decimals like 0.1?
One tenth cannot be written exactly in binary, so computers store an approximation. These calculators use exact integer arithmetic instead, which avoids that rounding error.
Which calculator should I use for schoolwork?
Choose the one that matches what you already have. If you have a fraction, use a "Fraction to" calculator; if you have a decimal, use a "Decimal to" calculator. Each shows the steps so you can compare your own method.