How to Convert HDR to G3 — Quick & Free
Fast, instant HDR to G3 (FAX) conversion. No signup required. Just drop your .hdr file and get .g3 in seconds.
Batch Settings
About HDR to G3 (FAX) Conversion
Short answer: yes, you can convert HDR to G3 online for free, and quality is well preserved with the right settings. Just upload your .hdr file to CocoConvert, pick G3 as the output, and click Convert. The whole process takes seconds.
Now for the details. HDR (Radiance) is a high-dynamic-range image format used in lighting and rendering. G3 is a widely used file format. Converting between these two formats lets you convert between formats quickly.
Your HDR file is decoded and re-encoded as G3. Converting HDR to G3 maintains high quality with CocoConvert's optimised encoder settings.
CocoConvert runs entirely online — no software to install, no account to create. Your files are encrypted during upload (TLS), processed on isolated servers in Germany, and permanently deleted after 24 hours. It works in Chrome, Safari, Firefox, Edge, and all mobile browsers.
Need to convert more than one file? Free users can do 5 per hour. Pro gets 100 per hour with files up to 5 GB each.
How to Convert HDR to G3 (FAX)
- 1
1. Upload HDR
Drop your .hdr file onto the page (or tap "Browse" on mobile). Add multiple files for batch conversion.
- 2
2. Select G3
Choose .g3 from the output dropdown. Settings are pre-configured for best results.
- 3
3. Convert
One click. The server handles all the heavy lifting using FFmpeg and Sharp.
- 4
4. Download
Your .g3 file is ready. Download it directly or get all files as a zip archive.
What Happens When You Convert HDR to G3 (FAX)
Your HDR file is decoded and re-encoded as G3.
Your HDR file is uploaded and validated
The file is decoded (parsed into its raw data)
The data is re-encoded in G3 format
The converted file is ready for download
Format Comparison
HDR
.hdr file
| Extension | .hdr |
| MIME Type | image/vnd.radiance |
| Category | Image |
G3 (FAX)
.g3 file
| Extension | .g3 |
| MIME Type | image/g3fax |
| Category | Image |
Should You Convert HDR to G3 (FAX)?
When to Convert
- ✓When you need a G3 file
Frequently Asked Questions
Is HDR to G3 conversion free?
Yes. CocoConvert offers free HDR to G3 conversion with generous daily limits — 25 minutes of processing time and up to 5 files per hour (250 MB each). Pro plans remove these limits.
How fast is HDR to G3 conversion?
Most files convert in 2–10 seconds depending on size. Large image files may take 30 seconds. Batch jobs process in parallel for maximum speed.
What happens to my files after conversion?
Your uploaded HDR file and the converted G3 file are both automatically deleted from our servers within 24 hours. They are never shared, sold, or analysed.
Does converting HDR to G3 lose quality?
Converting HDR to G3 maintains high quality with CocoConvert's optimised encoder settings.
Can I convert G3 back to HDR?
Yes, CocoConvert supports G3 to HDR conversion as well. However, if the original conversion involved lossy compression, converting back won't recover the lost data.
Versions are pinned in our worker Dockerfile and re-built via CI on every change.