BMP to G3 conversion is the process of transforming images stored in the BMP (Bitmap) raster format into the G3 (Group 3) facsimile compression format used primarily for black-and-white (bi-level) scanned images and faxes. This conversion typically involves reducing color/grayscale BMP data to a 1-bit bilevel image and encoding it with CCITT Group 3 compression for compact, fax-compatible output.
Related guides
Practical guides to help you choose formats, preserve quality, and avoid common conversion problems.
WebP has quietly become the default image format of the modern web, delivering 25-35% smaller files than JPG and PNG with universal browser support. This 2026 guide covers current adoption stats, browser compatibility, WordPress integration, conversion workflows, and when to choose WebP over AVIF for optimal Core Web Vitals performance.
Read guide →Not sure whether to save your image as PNG or JPG? This detailed comparison covers compression, transparency, file size, web performance, and real-world use cases so you can pick the right format every time — with conversion links when you need to switch.
Read guide →Learn how to convert HEIC to JPG for maximum compatibility. This guide explains what HEIC is, why iPhones use it, the key differences between HEIC and JPG, and walks through every conversion method including online tools, iPhone settings, Windows, and Mac.
Read guide →Drag your .BMP file from your computer or use the browse function.
Confirm .g3 as the selected destination format.
Click "Convert" and download your converted .G3 file once ready.
The BMP format uses the MIME type image/bmp and is an uncompressed raster image format widely used for storing bitmap digital images. G3 files typically use the image/g3fax MIME type and are designed for monochrome images, especially in fax and document scanning. The G3 codec applies compression algorithms to efficiently encode black and white images, reducing file sizes significantly.
The G3 (.G3) format is commonly used for image. Understanding its characteristics can be helpful when converting to or from other formats like BMP.
While specific technical details aren't available here, G3 files generally serve the purpose of storing image effectively within their domain.
Easily convert your BMP images to G3 format online with our user-friendly BMP to G3 converter. Perfect for those looking to reduce file sizes while maintaining essential image detail. No software installation necessary—just upload, convert, and download your files in seconds.
BMP files are uncompressed and typically larger, suitable for high-quality color images. In contrast, G3 is a compressed format optimized for monochrome images, commonly used in fax transmissions. Choosing G3 reduces storage needs but limits color information, ideal for black and white graphics.
Keep source BMPs under 10–20 MB per page when possible for faster conversion; very large high-resolution BMPs may take longer and consume more memory.
Preserve readability by converting color or grayscale BMPs to bilevel using adaptive thresholding or error-diffusion dithering rather than a single fixed threshold when the image has gradients.
For multi-page workflows, convert BMPs to TIFF with CCITT Group 3 compression or use batch tools that support 2D encoding to reduce output size and maintain fax compatibility.
Note format limitation: G3 is strictly for bilevel (black-and-white) images—color and continuous-tone detail will be lost during conversion to G3.
This BMP to G3 converter saved me tons of space without losing clarity.
James L.
Photographer
Quick and easy to use, perfect for converting scanned documents.
Anna M.
Office Manager
Reliable and fast, the online tool met all my conversion needs.
Daniel S.
Developer
Start your free BMP to G3 conversion now.
Drag your file here to to upload.
Up to 250MB
If you need archival quality, retain original BMPs or produce a lossless grayscale TIFF in addition to G3 for fax/distribution purposes.