How to convert PNM to PGM
To convert PNM to PGM, upload your PNM file, choose PGM as the output format and press Convert. The finished PGM file is ready to save to your phone or computer in seconds, free, with no watermark and no sign-up. Your file is deleted from our server about 30 minutes after the conversion.
This free online converter changes PNM images into PGM files in seconds, with no software to install and no watermark. You can convert several files at once, resize them and choose the quality for formats that support it. Metadata such as location tags is removed from the output for privacy.
Why convert PNM to PGM?
- Simple grayscale storage
- Easy to parse
- Good for algorithms and teaching
- Works with: GIMP, ImageMagick, Netpbm, OpenCV and MATLAB
What to expect from this conversion
- Both formats store the pixels without loss, so the picture stays identical. Only the file size and compatibility change.
- PGM stores only brightness, so the colour image is converted to grayscale.
- Browsers do not display PGM files, so use it in editors, print workflows or development tools rather than on a web page.
PNM vs PGM
| Property | PNM | PGM |
|---|---|---|
| Full name | Portable Anymap | Portable Graymap |
| Released | 1988, Jef Poskanzer (Netpbm) | 1988, Jef Poskanzer (Netpbm) |
| Compression | None (uncompressed) | None (uncompressed) |
| Transparency | No | No |
| Animation | No | No |
| Bit depth | 1, 8 or 16-bit | 8 or 16-bit gray |
| Shown in browsers | No | No |
| Best for | Unix-style image pipelines; teaching and research | grayscale processing; image-analysis research |
Steps to convert PNM to PGM
- Drop your PNM image file onto the converter, or click to choose it.
- Check that PGM is selected as the target and adjust the options if you want.
- Press Convert, then download your new PGM file when it finishes.
Tips for the best result
- Use quality 80 to 90 for photos: it is visually close to the original at a much smaller size.
- Set a width if the image will be shown on a small screen, which also reduces the file size.
- Choose a background colour before converting transparent images to a format without transparency.
Frequently asked questions
How do I convert PNM to PGM?
Drop your PNM files on the converter, confirm that PGM is the target and press Convert. Download each file or the whole batch as a ZIP.
Is the PNM to PGM converter free?
Yes. It is free with no watermark, no sign-up and no limit on how many images you convert. The site is supported by ads.
Does converting PNM to PGM reduce quality?
Both formats store the pixels without loss, so the picture stays identical. Only the file size and compatibility change. The quality slider only affects formats that use lossy compression.
Will transparency be kept when I convert PNM to PGM?
PNM images do not contain transparency, so there is nothing to lose. PGM does not support it either.
Which programs open PGM files?
PGM files open in GIMP, ImageMagick, Netpbm, OpenCV and MATLAB.
How many images can I convert at once?
Up to 20 images per batch, each up to 60 MB. Files are deleted from the server about 30 minutes after conversion.