Convert an image to black and white
Drops the color and keeps the brightness of every pixel: scans stay legible, flyers preview the way a black-only printer will print them, and JPGs get lighter.
Your images
Settings
Generated images
- Nothing uploaded
- Free, no sign-up
- Strips EXIF
- Batch files
The print shop is running your flyer in black ink only, and you want to see whether the orange logo still reads before paying for 500 copies. A scholarship portal wants transcript scans in grayscale and under 2 MB apiece. Or a portrait simply looks better without the color cast from the kitchen lights. All three are the same edit: keep each pixel's brightness, throw away its hue.
That is the one thing this page does. For every pixel it computes a gray value from the red, green and blue channels, weighted 29.9%, 58.7% and 11.4% (the Rec. 601 luma formula behind the Desaturate command in most photo editors), and writes that value back into all three channels. You get 256 levels from black to white, not the two-tone output of a scanner's Black & White setting, which is a different thing that some forms specifically ask for.
The side effect is usually welcome: a JPEG with nothing left in its color planes compresses to a smaller file at the same quality setting. Drop in one photo or forty scanned pages, keep JPG or switch to PNG, and the You saved counter shows how many kilobytes the color had been costing. The work runs on a canvas inside your tab, so a 30 MB scan is limited by your device's memory, not by an upload.
How it works
Grayscale is already switched on for this page. The format bar and the Quality slider are the only decisions left.
Drop in the photos or scans
Tap Choose images, drag files onto the box, or paste a screenshot with Ctrl+V on desktop. JPG, PNG, WebP, iPhone HEIC, GIF (first frame), BMP, SVG and AVIF (where your browser opens it) are all accepted, and every file in the batch is converted on its own.
Keep JPG, or pick PNG or WebP
JPG comes preselected because it gives the smallest file for photos and paper. Choose PNG for a logo with transparency or a screenshot of text; PNG ignores the Quality slider (30 to 100, default 82), which shapes JPG, WebP and AVIF. Type a Max width (px) if the pixels need to shrink as well.
Generate, check the savings, download
Click Generate images. Each card lists the old size, the new size, the percentage change, the output dimensions and an EXIF stripped tag; the You saved bar totals the whole batch. Save cards one at a time or hit Download all (.zip).
Grayscale, bitonal and color: which one the form is asking for
Scanner drivers, court clerks and print shops each mean something different by black and white. This page produces grayscale: 8 bits per pixel, 256 levels, every midtone intact. A scanner's Black & White or Text mode is bitonal: a threshold forces each pixel to pure black or pure white. That is the high-contrast scan some e-filing rules and fax gateways specify, and there is no threshold slider here to make it.
| Mode | Levels per pixel | What survives | Typical use |
|---|---|---|---|
| Grayscale (this page) | 256 | Shading, pencil, handwriting, photos | Forms, print proofs, portraits |
| Bitonal, 1-bit (scanner B&W mode) | 2 | Only pure black and pure white | Typed text, line art, fax |
| Color (RGB) | 16.7 million | Everything | Stamps, colored ink, charts, passport photos |
Why a blue sky turns dark and a yellow shirt turns light
The gray value is not a plain average. Green carries 58.7% of the weight, red 29.9% and blue only 11.4%, roughly how the eye judges brightness. So a clear sky comes out darker than it looked, foliage lightens, and a red and a green of similar brightness land on almost the same gray, so a red-and-green chart can lose its separation.
There are no contrast, brightness, sepia or channel-mix sliders: one fixed conversion. If a portrait looks flat, raise the contrast in a photo app first, then convert the exported file here. Filters do not stack either; for a black-and-white negative, save the gray version and run it through the invert page.
How much smaller the JPG gets, and when it gets bigger
A JPEG stores brightness in one plane and color in two more. After conversion those color planes hold a constant value, and constant data compresses to almost nothing. At the same Quality number a colorful photo typically drops 10 to 30 percent; a scan of black text on white paper, already nearly gray, barely changes. The output is still a three-channel JPEG, so a single-channel grayscale JPEG from Photoshop would be slightly smaller still.
PNG can go the other way: it is lossless, so a PNG built from a JPG original often ends up larger, gray or not. Nothing gets sharper either; JPEG blocks and noise in the original are still there, now in gray. Sides above 10,000 px are scaled down, and EXIF, including GPS and capture date, is removed from every output.
Documents and photos where the color is the evidence
The color original stays untouched on your device, so a test costs nothing. Some recipients will bounce a gray version, though:
- A notary seal, county stamp or blue-ink signature: in gray it reads as printed text and may be treated as a photocopy.
- Checks for mobile deposit: banking apps reject edited images.
- A U.S. passport or visa photo, which the State Department requires in color.
- Charts, maps and dashboards whose legend is the color.
- Product photos for a listing: proof the print in gray, list in color.
Frequently asked questions
Is this the same as scanning a document in black and white?
No. A scanner's Black & White (or Text) mode is bitonal: each pixel becomes pure black or pure white with no midtones. This page makes grayscale with 256 levels, which keeps handwriting and shading readable but produces a larger file than a bitonal scan.
Does converting to black and white make the file smaller?
For JPG, usually yes: the two color planes of the JPEG become flat and compress to almost nothing, so a colorful photo typically loses 10 to 30 percent at the same Quality setting. A scan that was already mostly gray changes little. The You saved bar reports the real number.
Can I get the color back later?
Not from the converted file; the hue is discarded for good. The original you dropped in is never modified and is still on your device, so keep that as the color master.
Why does my black-and-white photo look flat instead of dramatic?
This conversion only maps brightness. It applies no contrast curve and no red or yellow filter the way a film photographer or Lightroom's B&W mix would. Add contrast or a color filter in a photo app first, then convert the exported file here.
Can I get pure black and white with no gray at all?
No. There is no threshold slider on this page. For a 1-bit, no-gray image use your scanner's Black & White or Text mode, or the Threshold command in an image editor.
Will a transparent PNG logo stay transparent?
Yes, as long as the output is PNG or WebP: only red, green and blue are recalculated and the alpha channel is untouched. Choose JPG and the transparent area is filled with white before conversion, because JPEG has no transparency.
Can I convert a whole stack of scanned pages in one go?
Yes. Add every page at once; there is no file-count limit beyond your device's memory. Each page comes out as its own file, Download all (.zip) bundles them, and the JPG to PDF page can then merge the gray pages into a single PDF.
Do my tax forms or medical records leave my computer during the conversion?
No. The file is decoded, recalculated pixel by pixel and re-encoded on a canvas in your browser tab, and no copy is transmitted anywhere. The one thing the site fetches, once, is a small HEIC decoder if you open an iPhone HEIC file.