Code 128 Specifications & Data Sheet

Specifications | Overview | Manual Check Character Calculation

Code 128 Barcode Symbology Data Sheet

Three different start characters are used with Code 128 Barcodes to tell the barcode reader which character set is in use. If using character sets A or B, create the output by selecting the Code 128 font and entering the appropriate letter from the keyboard with the exception of the space character barcode, extended functions and the start / stop characters. For more information on this function, please view the page on printing extended barcode characters.

The data sheet below illustrates the three different character sets and the ASCII location to print the character. Listed in columns A, B and C are the character or function the barcode scanner will read for the associated symbol. The columns ASCII, Char and Unicode are unique to IDAutomation Code 128 Barcode Fonts. These columns designate the location in either ASCII or Unicode where the barcode symbol for the character resides. The column Char lists the character that resides at the ASCII location, which can be used to print the corresponding symbol. The IDAutomation character set provides easy methods of encoding functions such as returns and tabs in the barcode.

* Windows cannot print a symbol instead of a space character from Visual Basic and most other development environments. Use ASCII 194 instead of ASCII 32 to create the Code 128 space character.

** Mac systems should print the Code 128 font from Unicode locations if possible because the extended characters map to different characters than what is displayed on the "Char" column in Mac Roman encoding. Visit the Code 128 FAQ page for more information.

Manual Code 128 Check Character Calculation

NOTE: IDAutomation provides Free Font Encoders and Source Code Samples that format the start, stop and check characters to Code 128 Barcode Fonts. Thus, manual check digit calculations are usually not necessary.

The check character is positioned after the data characters and just before the stop character. To determine the value of the check character:

1. Reference the table above to obtain the value of the start character and all data characters.
2. Assign a weight to each data character (not the start character, just the data characters.) The weighting starts at 1 and increases by one for each data character.
3. Multiply the character values by their weights for the data characters.
4. Find the sum of the start character and all data character weights and divide by 103.
5. Use the above data sheet to locate the character that has the value of the total in #4. Use this as the check character.

Calculating Character Set A or B

The table below shows an example of how to obtain the check character for the data "biz" using Code 128 character set B.

1. Calculate Total: 104 + (66*1) + (73*2) + (90*3) = 586
2. Calculate Checksum: 586 divided by 103 = 5 remainder of 71. Check digit = value of 71. The character to print for the value of 71 is "g" or ASCII 103.

To encode extended ASCII characters from the keyboard that do not have keys defined, use the ALT+<xxxx> key combination, where xxxx equals the character's ASCII location in 4 digits. For example, to type ASCII character 104 into Microsoft Word, select the font in Word, press the ALT key and while holding it down type 0104 on the keypad of the keyboard. The keypad must be used to do this. 

To encode the data "biz" as a barcode, type: ALT 0204, b, i, z, g, ALT 0206 or ÌbizgÎ. Click here for more information on encoding fonts with extended ASCII characters or use IDAutomation's Free Font Tools.

Calculating Character Set C

The table below is an example of how to obtain the check character for "667390" using Code 128 Character Set C. First, the number will have to be interleaved into pairs and then the appropriate character that represents the number pair should be selected.

1. Calculate Total: 105 + (66*1) + (73*2) + (90*3) = 587
2. Calculate Checksum: 587 divided by 103 = 5 remainder of 72. Check digit = value of 72. The character to print for the value of 72 is ASCII 104.

To encode "667390" as a barcode, type: ALT 0205, b, i, z, h, ALT 0206 or ÍbizhÎ.

Switching Character Sets Within a Barcode

It is possible to switch between character sets in a single Code 128 barcode symbol. Although character set B can encode text and numbers, it may require the user to switch to set A to encode a function such as a tab or carriage return.

The table below provides an example of how to encode "biz" using Code 128 Character Set B, then switch to Character Set A for a carriage return function.

1. Calculate Total: 104 + (66*1) + (73*2) + (90*3) + (101*4) + (77*5) = 1375
2. Calculate Checksum: 1375 divided by 103 = 13 remainder of 36. Check digit = value of 36. The character to print for the value of 36 is "D" or ASCII 68.

Switching between character sets can also be done with IDAutomation Free Font Tools. For example, if the data is bizÉm (É is the switch to set A and m is the function according to the chart) as the input for the Code 128 B function. The data ÌbizÉmDÎ would be returned, which would perform the switch to set A and the function of a return when created with IDAutomation fonts and scanned by a barcode scanner.

Calculating for UCC/EAN-128

The FNC1 is treated as a different character, so the calculation will have to be figured in. Here is how to calculate (00)1234(15)12 which would be Ê001234Ê1512 in IDAutomation's Font Tools. Look at the chart to pair up the numbers with letters. More information about creating UCC/EAN128 barcodes is provided in the Code 128 FAQ.

1. Add up totals: = 1063
2. Calculate Checksum: 1063 divided by 103 = 10 remainder of 33. Check digit = value of 33.

According to the chart, ÍÊÂ,BÊ/,AÎ will be needed to create the barcode from the font.

Code 128 Barcode Specifications

The X dimension (X is the width of the narrow bar) is listed below for various point sizes.

IDAutomation Code 128 Barcode Fonts have been specially designed to produce dependable and scanable barcodes when printed at large and small point sizes. The Code 128 font can be printed as small as 6 points with a 600 DPI laser printer, assuming the barcode scanner can read a barcode that small. IDAutomation testing has dependably scanned very small Code 128 Barcodes with the IDAutomation Plug 'n Play USB Barcode Scanner - as small as 4 points.

Please be aware that Code 128 fonts should be printed at 12 points or larger for open systems.

Eighteen different versions of Code 128 Barcode Fonts are provided to support human-readable versions and different height/width requirements. Fonts with the letter "H" in the font name are "human readable" versions more about these versions. The last characters in the Code 128 barcode font name determines the height of the barcode with the shortest being "XS" and the tallest being "XXL". Because each font can be printed at various point sizes, there are several combinations of heights and widths that can be produced. (Click to view font names prior to July, 2003)

Font Names Prior to July, 2003

Code 128 Font Installation Instructions

Note: When printing the Code 128 fonts at less than 15 points, a high quality printer with a 600 DPI or greater resolution should be used. It may also be necessary to reduce the print intensity if it has been increased.

1. To install TrueType Fonts in Windows, run the Install.exe file included in the download. Otherwise, proceed to step 2.
2. Click on Start, select Settings and click on Control Panel.
3. Click on Fonts. Click on File in the main tool bar; select Install New Font.
4. Select the folder where the Code 128 Font is saved.
5. The Code 128 Font will appear and look like this: IDAutomationSC128XS (TrueType) Select this font and click OK.
6. Click Start and restart the computer.
7. The Code 128 Barcode Font should be active when the computer is restarted.

Installing Fonts on Mac OS X:

1. Drag or copy and paste the TrueType font file(s) ending in TTF to the Library/Fonts folder.
2. Restart the application to activate the fonts, although some applications may require a system reboot.
3. The Code 128 Barcode Font should now be active in the font menu of the application.

Installing TrueType Fonts on the Classic Mac (OS 7.1 - OS 9):

1. If an expander utility is not already loaded to open ZIP files and decode MacBinary files, download and install Stuffit Expander for Mac.
2. Open the ZIP distribution file that contains the fonts by dragging the ZIP file on the Stuffit Expander icon. The font files will be extracted from the ZIP distribution file and will appear in a subfolder of the folder the ZIP file was placed in. Open this subfolder to view the font files.
3. Please view the documentation supplied with the font files. To do so just drag the file "readme.html" to the Safari or Mozilla Firefox icon.
4. Now the files must be decoded from MacBinary format. Drag the font files desired that end with "mtt" to the Stuffit Expander icon.
5. Then drag the decoded font files to the System - Fonts folder.
6. Restart the application to activate the fonts, although some applications may require a system reboot.

Additional Resources

• Font Installation Procedures for Other Operating Systems

If there are any questions or assistance needed, please contact IDAutomation.

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