Convert an Image to Grayscale
Pick an image — it's converted to grayscale in your browser, nothing is uploaded.
Convert Images to Grayscale Instantly
Remove color from any image directly in your browser — no software to install, no files sent to a server. Your image stays on your device the entire time.
How It Works
Upload a JPEG, PNG, WebP, or other image format. The tool uses ffmpeg (compiled to
WebAssembly) to apply the format=gray filter, stripping all color information and
producing a true grayscale output in the same format as the input.
Why Grayscale?
Grayscale images are smaller, work well for printing, and are commonly used in design workflows, document scanning, and artistic effects. Converting to grayscale is also a first step in many computer-vision preprocessing pipelines.
Supported Formats
JPEG, PNG, WebP, GIF, BMP, and most other common image formats supported by ffmpeg. The output keeps the same file format as the input.
FAQ
Does the converted image keep my original format?
Yes. The tool applies ffmpeg's format=gray filter and writes the result using the
same extension as the input — a PNG comes back as a PNG, a JPEG as a JPEG. The
downloaded file gets a -gray suffix, so photo.jpg becomes photo-gray.jpg.
Is there a maximum image size?
Yes — the input image is capped at 4 MiB, and the grayscale output must also fit within 4 MiB. Larger files are rejected before conversion starts. If your image is over the limit, resize or compress it first.
Will a transparent PNG keep its transparency?
No. The gray pixel format has no alpha channel, so transparent areas are flattened
during conversion. If you need grayscale with transparency preserved, keep a copy of
the original alpha mask to re-apply in an image editor.
Is my photo uploaded anywhere during conversion?
No — ffmpeg runs as WebAssembly inside your browser tab, so the pixels never leave your device. Closing the page discards everything.
Developer & Automation Access
Run it from the terminal
Same engine as this page, headless — via the gizza CLI:
gizza tool image-grayscale 'url=https://example.com/input'New to the CLI? Get gizza →
Open it by URL
Pre-fill and auto-run this tool with query parameters — the names match the API/CLI:
https://gizza.ai/tools/image-grayscale/?url=https://example.com/inputMachine-readable descriptor: tool.json — title + parameters JSON Schema for agents.