Add and subtract
Compute a/b ± c/d as (ad ± bc)/bd, then reduce with GCD.
065 · UNIT & CALCULATOR
Fraction & Decimal Calculator
Calculate fraction operations, simplify fractions, and convert exactly between fractions and decimals with rational arithmetic.
LOCALCALCULATE IN YOUR BROWSER
Use 3/4 for a fraction, 1 1/2 for a mixed number, or 5 for an integer.
Decimal precision12
RESULT · Simplified fraction
Enter a value and calculate.
HOW TO USE
How to use
- 01
Choose Operations, Simplify, Fraction to Decimal, or Decimal to Fraction.
- 02
Enter fractions as 3/4, mixed numbers as 1 1/2, or integers as 5.
- 03
For operations, enter two values and choose +, −, ×, or ÷.
- 04
Calculate to see the simplified fraction, mixed number, and decimal together.
- 05
Open Working to verify the calculation flow and copy the result when needed.
CALCULATION GUIDE
Keep fraction arithmetic exact instead of routing through floating point
Integer numerators and denominators, GCD reduction, and string-based decimal conversion keep exact calculation separate from display precision.Multiply
Compute a/b × c/d as ac/bd and reduce the final result.
Divide
Turn a/b ÷ c/d into a/b × d/c. A zero second value is rejected.
Mixed numbers
Normalize 1 1/2 to 3/2 internally and also provide a mixed-number result.
Decimal to fraction
Build 625/1000 directly from 0.625, then reduce it to 5/8.
Repeating decimals
Keep 1/3 exactly as a fraction and apply precision only to the decimal display.
IMPORTANT NOTES
Important notes
- Calculations use integer numerator/denominator rational arithmetic and every fraction result is reduced with GCD.
- A zero denominator and division by zero are rejected.
- Finite decimal-to-fraction conversion uses the exact decimal input string rather than reverse-engineering a floating-point value.
- Repeating values such as 1/3 are displayed to up to 12 decimal places and marked with an ellipsis.
- Scientific notation is excluded from the first release.
- Numerator and denominator are limited to 100 digits each; input strings are limited to 120 characters.
FAQ
Frequently asked questions
01What is 1/2+3/4?+
It is 5/4, or 1 1/4 as a mixed number, or 1.25 as a decimal.
02How does 12/18 simplify?+
Divide numerator and denominator by GCD 6 to get 2/3.
03What is 0.625 as a fraction?+
625/1000 reduces to 5/8.
04Can 1/3 be shown exactly as a decimal?+
It repeats forever, so the first release shows a fixed display precision followed by an ellipsis.
05Can I enter mixed numbers?+
Yes. Input 1 1/2 and it is normalized internally to 3/2.