Free Online UPC A Barcodes Generator

Generating & Printing UPC-A Barcode Images Online

Online UPC A Generator is developed based on OnBarcode .NET Barcode Generator Component.

NOTE

We are providing free online streaming barcode generation service. Now you can generate barcode image through the following url:

http://generator.onbarcode.com/linear.aspx?TYPE=4&DATA=123456789

To get this free online service, please contact us support@onbarcode.com

Watch a quick video tutorial and get started

NOTE

The barcode generator is locked, and you cannot change barcode settings. To unlock it, please go to our YouTube online barcode generator video description section to get the free keycode.

Free barcode generator online video tutorial:
https://youtu.be/hs_ZME55p2Q

UPC-A Barcode Settings
Type:
Barcode Encoding Data
UPC-A supplement data (The value is 2 or 5 digits)
UPC-A supplement bar height
UPC-A supplement bar space with main bar

UPC-A Barcode Text Style
Show Text
Text margin
Text Font Name
Text Font Size
Text Font Style
Text Color

Barcode Colors
Back Color
Fore Color

Unlock Keycode
Code

UPC-A Barcode Image Size Settings
Enable Auto Resize
Bar Alignment
Unit of Measure
X (bar module width)
Y (bar module height)
Left Margin
Right Margin
Top Margin
Bottom Margin
Resolution (in dots per inch)
Rotate
Barcode Image Width (if image width is smaller than the barcode minimum width, the setting will be ignored)
Barcode Image Height (if image height is smaller than the barcode minimum height, the setting will be ignored)
Image Format

Online Barcode Generator Supporting Bar Code Types

OnBarcode barcode products

OnBarcode also provides the following libraries and components for generating, printing, scanning, and reading UPC A barcodes.

Barcode Software & Libraries

OnBarcode provides professional barcode software and libraries for you.

Barcode in .NET Crystal Report - barcode library to create, generate barcodes in .NET Crystal Reports easily.
Barcode Reader in Java - barcode dll to easily scan, read barcode images in Java applications.
Barcode in Java - how to create, generate best barcode images in Java projects.
Barcode Reader in .NET - barcode library sdk to read, scan barcode images in various .NET applications.
Barcode Reader in .NET Guide - how to accurately scan, read barcodes in ASP.NET, Visual C# or VB.NET projects.
Barcode in ASP.NET - barcode dll library to create barcodes in ASP.NET web form / web site using web control or Microsoft IIS.
Barcode in .NET WinForms - barcode library to print, generate barcodes in .NET WinForms applications.
Barcode for .NET WinForms Guide - how to create barcodes in .NET winforms with detailed examples.
Barcode for C# - how to create, generate high-quality linear & 2D barcodes in Visual C# programs with sample codes.
Barcode for VB.NET - how to generate, print barcodes in VB.NET applications using Visual Basic .NET sample codings.
Barcode for .NET - professsional barcode generator library SDK to create, generate barcodes in .NET projects.
Barcode for .NET Guide - how to easily create 1D, 2D barcodes in .NET applications with detailed examples.

QR Code Software & DLLs

OnBarcode provides QR Code software and libraries for you with outstanding quality.

.NET QR Code Reader - mature QR Code recognition control to read QR Code 2D barcodes in .NET applications.
.NET QR Code Generator - high-quality barcode dll to create QR Code barcodes in .NET projects without other tools.
ASP.NET QR Code Generator - generating QR Code barcode images in ASP.NET web application.
C# QR Code Generator - programmatically create QR Codes using Visual C# in windows / ASP.NET web applications.
VB.NET QR Code Generator - using Visual Basic / VB.NET to generate and create QR Code in VB.NET programs.
Java QR Code Generator - easy to use Java QR Code generating library (jar) for Java barcoding applications.

UPC-A Software & Components

OnBarcode provides several UPC-A barcode generating component, library, and SDK for you.

ASP.NET UPC-A - examples to create, print barcodes in ASP.NET web applications / website & web form.
.NET UPC-A - sample codes to create ISSN bar codes in Visual Studio .NET projects.
C# UPC-A - simple Visual C# .NET sample code to print ISSN 1D barcodes in C#.NET applications.
VB.NET UPC-A - creating ISSN linear barcodes in Visual Basic. NET applications.

How to Generate free Code 39 Barcode online?

This comprehensive technical guide offers a step-by-step approach to generating, customizing, and validating UPC-A (Universal Product Code Version A, a 12-digit linear barcode symbology used globally for retail product identification) in online web browser and web application. It covers quick UPC-A generation workflows, web-specific customization options, and check digit calculation.

Customize UPC-A Barcodes for Online Web Applications

Using the OnBarcode Online Barcode Generator software, you can customize UPC-A barcodes to fit your online web application's UI design and retail requirements.

Key UPC-A Customization Options

ShowQuietZoneIndicator: Controls whether to display or hide the UPC-A quiet zone indicator (marks at the ends of the barcode). The default value is true; disable it for a cleaner web UI.
UPCEANLeadDigitSpace: Adjusts the space between the first digit and the start character bar. The default value is 0; increase it for better web readability.
UPCEANTrailDigitSpace: Adjusts the space between the stop character bar and the quiet zone indicator. The default value is 0; increase it for better web readability.
UPCEANLeadTrailDigitSizeRatio: Controls the font size of the first and last digits relative to the rest of the digits. The default value is 1.0f (same size); adjust for web UI consistency.

Customizing UPC-A Quiet Zone Indicator

The quiet zone indicator is displayed by default, but you can hide it to streamline your web application's UI:

Use the Show Quiet Zone Indicator property and set it to false.
This is useful for web UIs where space is limited (e.g., product thumbnails, compact inventory labels).

Customizing UPC-A Digit Spacing, Vertical Offset, and Font Size

ou can fine-tune the position and size of the first and last digits to improve web display and readability using the following properties:

UPCEANLeadDigitSpace: Increases the space between the first digit and the start bar (web-friendly for better separation).
UPCEANTrailDigitSpace: Increases the space between the stop bar and the quiet zone indicator.
UPCEANLeadDigitYShift: Adjusts the vertical offset of the first digit (negative values shift it upward, positive values shift it downward) for web UI alignment.
UPCEANTrailDigitYShift: Adjusts the vertical offset of the last digit for web UI alignment.
UPCEANLeadTrailDigitSizeRatio: Modifies the font size of the first and last digits relative to the rest (e.g., 0.6f makes them 60% of the standard size) for web UI consistency.

Note: Avoid excessive spacing or vertical offsets, as they may distort the barcode's proportions. Test customizations across multiple web browsers and devices to ensure scanning reliability.

Calculating UPC-A Check Digit for Web-Based Data Accuracy

The UPC-A check digit is a critical component for ensuring data accuracy in online web applications. It is calculated using a module 10 algorithm, based on the weighted sum of the UPC's digits (retail number system, manufacturer code, and product code).

Step-by-Step Check Digit Calculation

Consider the right-most digit of the 11-digit UPC-A data as being in an "odd" position.
Assign odd/even positions to each digit by moving from right to left (e.g., 11th digit = odd, 10th = even, 9th = odd, etc.).
Sum all digits in odd positions, then multiply the result by 3.
Sum all digits in even positions.
Add the two totals (from steps 3 and 4) together.
The check digit is the number that, when added to this combined total, results in a number evenly divisible by 10.
If the combined total is already evenly divisible by 10, the check digit is "0" (not 10).