Formula and calculation method
a/b ± c/d = (ad ± bc)/bd. Multiplication = ac/bd. Division = ad/bc. Reduce by the greatest common divisor.
Use consistent units for all comparable inputs. The displayed result is rounded; arithmetic is performed with the full available numeric precision. Check your source measurements before relying on the result.
How to use fraction calculator
- Set First numerator. The example below uses 1.
- Set First denominator. The example below uses 2.
- Set Operation by choosing the option that matches your calculation.
- Set Second numerator. The example below uses 1.
- Set Second denominator. The example below uses 3.
- Select Calculate to update the result. Reset restores the illustrated inputs. Copy, print or download your own result if you need a record.
Worked example
Example inputs
- First numerator
- 1
- First denominator
- 2
- Operation
- Add
- Second numerator
- 1
- Second denominator
- 3
- Reduced fraction
- 5/6
- Decimal
- 0.83333333
Factors affecting your result
Use consistent units for all comparable inputs. The displayed result is rounded; arithmetic is performed with the full available numeric precision. Check your source measurements before relying on the result.
Changing first numerator changes the scenario being evaluated. Adjust one input at a time when comparing results, keep a copy of the assumptions, and compare values using the same unit and period. A precise arithmetic result does not make an uncertain assumption precise.
Frequently asked questions
How does the fraction calculator work?
a/b ± c/d = (ad ± bc)/bd. Multiplication = ac/bd. Division = ad/bc. Reduce by the greatest common divisor.
What inputs does Fraction Calculator need?
Enter first numerator, first denominator, operation, second numerator, second denominator. Choose values that correspond to the same situation and measurement convention.
How should I interpret the fraction calculator result?
Use consistent units for all comparable inputs. The displayed result is rounded; arithmetic is performed with the full available numeric precision. Check your source measurements before relying on the result.
Are my fraction calculator inputs uploaded?
No. The calculation runs in this browser. Favorites, recent tool names, theme and formatting preferences may be saved locally, but calculation inputs are not sent to a calculation server or stored by this website. Shared links do not include entered values.
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