Greatest Common Factor Calculator: Tool to Find GCF of Numbers

Greatest Common Factor Calculator Sign

This free online greatest common factor tool will find the GCF of 2, 3, or 4 numbers at once with the click of a button.

Plus, in addition to displaying the GCF, the calculator will also display the GCF divisors, and all factors for the numbers entered.

Also, if you would ever like to save some time when attempting to find the least common multiple (LCM) for up to 4 numbers, be sure to check out my Least Common Multiple Calculator.

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Greatest Common Factor Calculator

Calculate greatest common factor for up to 4 numbers at one time.

Special Instructions

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Selected Data Record:

A Data Record is a set of calculator entries that are stored in your web browser's Local Storage. If a Data Record is currently selected in the "Data" tab, this line will list the name you gave to that data record. If no data record is selected, or you have no entries stored for this calculator, the line will display "None".

DataData recordData recordSelected data record: None
1st #:1st number:First number:First number:

1st number:

Enter the first of the numbers to find the greatest common factor for. Number entered should be an integer greater than zero.

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2nd #:2nd number:Second number:Second number:

2nd number:

Enter the second of the numbers to find the greatest common factor for. Number entered should be an integer greater than zero.

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Opt 3rd #:Optional 3rd #:Optional third number:Optional third number:

Optional 3rd number:

Enter the optional 3rd of the numbers to find the greatest common factor for. In order to include the 3rd number, the 1st and 2nd numbers are required. Number entered should be an integer greater than zero.

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Opt 4th #:Optional 4th #:Optional fourth number:Optional fourth number:

Optional 4th number:

Enter the optional 4th of the numbers to find the greatest common factor for. In order to include the 4th number, the 1st, 2nd, and 3rd numbers are required. Number entered should be an integer greater than zero.

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GCF:GCF:Greatest common factor:Greatest common factor:

Greatest common factor:

This is the greatest common factor for the numbers you entered. If the result is one, it means that your entries do not have any factors in common other than one -- meaning no reduction or simplification is possible.

If you would like to save the current entries to the secure online database, tap or click on the Data tab, select "New Data Record", give the data record a name, then tap or click the Save button. To save changes to previously saved entries, simply tap the Save button. Please select and "Clear" any data records you no longer need.

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Help and Tools

Learn

Factors, common factors, and greatest common factors.

What are Factors?

The factors of a number is the set of all non-zero numbers that divide into the number evenly. For example, the factors of the number 12 would be as follows:

Factors of 12: 1, 2, 3, 4, 6, 12

Because ...

1 x 12 = 12
2 x 6 = 12
3 x 4 = 12

What are Common Factors?

Common factors occur when two or more numbers share one or more of the same factors. For example, the numbers 12 and 20 have the following factors, with the common factors appearing in orange:

Factors of 12: 1, 2, 3, 4, 6, 12

Factors of 20: 1, 2, 4, 5, 10, 20

What is a Greatest Common Factor?

The greatest common factor (A.K.A: GCF, Greatest Common Divisor, GCD) is the highest factor that two or more numbers share. Referring back to the numbers 12 and 20, the GCF would be 4 based on the following set of common factors:

Common Factors of 12 & 20: 1, 2, 4

How is Finding the Greatest Common Factor Useful?

The most common use of finding the GCF is for reducing or simplifying fractions, which we will cover on the various fraction calculator pages.

And that's all there is to understanding Greatest Common Factors.

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Adjust Calculator Width:

Move the slider to left and right to adjust the calculator width. Note that the Help and Tools panel will be hidden when the calculator is too wide to fit both on the screen. Moving the slider to the left will bring the instructions and tools panel back into view.

Also note that some calculators will reformat to accommodate the screen size as you make the calculator wider or narrower. If the calculator is narrow, columns of entry rows will be converted to a vertical entry form, whereas a wider calculator will display columns of entry rows, and the entry fields will be smaller in size ... since they will not need to be "thumb friendly".

Show/Hide Popup Keypads:

Select Show or Hide to show or hide the popup keypad icons located next to numeric entry fields. These are generally only needed for mobile devices that don't have decimal points in their numeric keypads. So if you are on a desktop, you may find the calculator to be more user-friendly and less cluttered without them.

Stick/Unstick Tools:

Select Stick or Unstick to stick or unstick the help and tools panel. Selecting "Stick" will keep the panel in view while scrolling the calculator vertically. If you find that annoying, select "Unstick" to keep the panel in a stationary position.

If the tools panel becomes "Unstuck" on its own, try clicking "Unstick" and then "Stick" to re-stick the panel.