The quickest way to convert a color image to black and white is to drag its saturation slider to zero in any photo app, but that is only one route and rarely the best-looking one. How to convert a color image to black and white really depends on your device and how much control you want, because black and white means three different things and picking the wrong one is why the result disappoints.
This guide covers every real method, on a phone, in a free desktop app, in Photoshop, in Microsoft Office, and in a browser editor, then explains what the change does to your file size and the print case that no other page bothers with. For the wider set of image conversions on this site, see the image conversion hub.
What is the difference between grayscale and true black and white?
Black and white splits into three distinct things: grayscale, which keeps every tone but no color; true black and white, which is pure one-bit monochrome with no gray at all; and a controlled conversion, which keeps a full range of grays while letting you decide how each color becomes a shade. Most tools, and even the answer box at the top of Google, use the terms interchangeably, which is exactly why people get a result they did not expect.
| Type | What it stores | Your control | Best for |
|---|---|---|---|
| Grayscale | Black, white, every gray between | None, a fixed mix | Quick looks, scans, documents |
| True black and white (1-bit) | Only pure black and pure white | None, a hard threshold | Line art, logos, fax-style output |
| Controlled (adjustment layer) | Full tonal range | Full, per color | Photos you want to look considered |
Grayscale: every tone, no color
Grayscale removes color and reproduces black, white, and all the shades of gray in between, and nothing more. It gives you no say in how a red or a blue becomes gray, since the software decides for you. That is fine for a receipt, a document scan, or a quick preview, and it is what most people actually want when they say black and white.
True black and white: one bit, pure monochrome
True black and white, in the strict sense, is a one-bit image: every pixel is either full black or full white, with no gray at all. A Reddit thread titled "convert to pure black and white (not grayscale)" ranks on this exact search because the distinction trips people up. You want real one-bit output only for line art, a logo, or a scan headed for a fax-style workflow. Run a photograph through a hard black-and-white threshold and the midtones collapse into blotches.
Black and white with control
The third meaning is the one photographers care about. A controlled conversion starts from a default grayscale mix, then lets you push each original color lighter or darker on its own, so a blue sky can go dramatically dark while skin tones stay natural. It keeps the full range of grays. It just hands you the wheel instead of deciding for you.
How to convert a color image to black and white on any device
To convert a color image to black and white on a phone, open the photo in your Photos app, tap Edit, and either apply a black and white filter or slide Saturation to zero. Both iPhone and Android ship this in the stock app, so you rarely need to install anything for a quick conversion.
On iPhone: filters or Saturation to zero
On an iPhone, open the shot in Photos, tap Edit, then tap the filters icon and choose Mono, Silvertone, or Noir for a one-tap look. For a cleaner result, tap the Adjust icon instead, scroll to Saturation, and drag it to zero, which drains the color without baking in a filter's contrast curve. This is the fastest way to convert a color photo to black and white when you are working from the phone that took the shot.
On Android: the Photos app Mono filter
On Android, the stock Google Photos editor does the same job: open the image, tap Edit, open Filters, and pick a monochrome preset, or open Adjust and pull Saturation down to zero. The menu names shift a little by phone maker, but every current Android Photos app has both a filter and a saturation control. Save creates a copy by default, so the original color file stays intact.
None of these shrink the file much, which surprises people. If a smaller upload is the actual goal rather than the monochrome look, compress the original instead, which typically cuts a phone photo 60 to 80 percent, far more than draining its color ever will.
Free desktop methods: Mac Preview, Windows, and GIMP
You do not need paid software to convert a picture to black and white on a computer. Mac Preview, the Windows Paint and Photos apps, and the free editor GIMP all do it, with no account and no upload.
Mac: Preview's Adjust Color panel
On a Mac, Preview handles this without any extra install. Open the photo, open the Markup toolbar, and click the Adjust Color icon, then drag the Saturation slider all the way to the left to drain every color to black and white (Cult of Mac). Use Auto Levels or the exposure sliders if the result looks flat, then export. It is one slider rather than six, but it costs nothing and needs no software beyond what already ships on the machine.
Windows and GIMP: free, no account
On Windows, the built-in Photos app dropped its old black and white toggle, which is a common complaint, so the reliable free routes are Paint 3D's effects or the free, open-source GIMP. In GIMP, open the image and choose Colors, then Desaturate, then Desaturate again, and pick a mode such as Luminosity for the most natural result. GIMP also carries a full mono panel under Colors if you want per-color control like Photoshop's, at no cost.
The Photoshop methods: quick grayscale versus full control
Photoshop gives you two very different conversions: Grayscale mode, which throws the color away instantly, and a Black and White adjustment layer, which keeps your original intact and hands you per-color control. Use the first for speed, the second for anything that needs to look good.
Convert image to grayscale the fast way
The fastest route is to convert image to grayscale directly: go to Image, then Mode, then Grayscale, and click Discard when Photoshop asks whether to drop the color information (Photoshop Essentials). It is a one-way door. Grayscale mode reproduces black, white, and gray with the mix decided for you and no way to adjust it, which is why Photoshop itself recommends the Black and White adjustment instead whenever the result needs to look considered rather than just fast. Work on a copy, because once you flatten and save, the color is gone.
The Black and White adjustment layer, for control
For control, add an adjustment layer instead: Layer, then New Adjustment Layer, then Black and White. Photoshop lays down a default grayscale conversion that you then shape in the Properties panel (Adobe Help Center). Drag the per-color sliders to make reds darker or yellows brighter, choose a preset for a starting point, hit Auto for a mix based on the image, or tick Tint for a subtle sepia cast. Because it sits on a layer above the original pixels, you can hide or delete it and your color photo is back, untouched.
Converting in Microsoft Office and browser editors like Canva
If your image already lives in a Word, PowerPoint, or Excel file, you do not need a separate editor at all. Click the picture, open the Picture Format tab, choose Color, and pick Saturation 0%, which is the same official method Microsoft points people to and the reason it matters that the Windows Photos app removed its own black and white option (Microsoft Learn). Browser tools like Canva and Adobe Express do the same job online with named filter presets.
In Word, PowerPoint, and Excel
Select the image, go to the Picture Format tab, click Color, and under Color Saturation choose 0%. The picture goes black and white in place, and the change is non-destructive: set saturation back to 100% and the color returns, because Office keeps the original embedded. This is the most direct route for a chart, a logo, or a photo that is already sitting inside a document.
In Canva or Adobe Express
In a browser black and white photo editor like Canva, select the image, open Edit, choose Filters, and pick a mono preset. Canva names several distinct ones, such as Classic, Noir, and Film, rather than offering a single toggle. Adobe Express works the same way and adds a duotone option. These are the easiest routes when you have no software installed and just want a good-looking result in a browser tab.
Does converting to black and white make the file smaller?
Less than you would think. Dropping color from an uncompressed image cuts its storage by about two-thirds, but a compressed JPEG barely moves, because JPEG already compresses color far more aggressively than brightness. If your goal is a smaller file, change the format or the quality, not the color.
Here is the arithmetic on a 12-megapixel photo, which is 4000 by 3000, or 12 million pixels. Stored as an uncompressed 24-bit color bitmap, that is 3 bytes per pixel, about 36 MB. As 8-bit grayscale it is 1 byte per pixel, about 12 MB, a two-thirds cut. As true one-bit black and white it is one-eighth of a byte per pixel, about 1.5 MB. Those three numbers are the three meanings of black and white, in bytes.
| Same 12 MP image, uncompressed | Storage |
|---|---|
| 24-bit color (RGB) | about 36 MB |
| 8-bit grayscale | about 12 MB |
| 1-bit true black and white | about 1.5 MB |
That two-thirds saving is real for bitmaps and for PNG-style formats. It mostly vanishes the moment JPEG is involved. JPEG splits an image into brightness and color, then compresses the color channels hard, because the eye notices brightness detail far more than color detail. By the time a color photo is a normal JPEG, most of its color data is already gone, so the grayscale version of the same shot usually lands within a few percent of it, not a third smaller. If a smaller file is the point, changing the color is the wrong lever.
Converting black and white for printing
For printing, black and white for printing is almost always grayscale, not true one-bit monochrome, unless you are printing line art. A photo printed as one-bit comes out as harsh dots, while printed as grayscale it keeps its tones. Export at the printer's resolution, commonly 300 DPI, and keep the file in a format that holds a full tonal range.
Two things matter for print that never come up on screen. First, resolution: a photo that looks fine on a screen at 72 to 96 DPI needs roughly 300 DPI at print size, so a 4 by 6 print wants about 1200 by 1800 pixels. Second, format: save print-bound black and white as a high-quality JPEG, a PNG, or a TIFF, never a heavily compressed web JPEG, because print reveals banding that a screen hides. If the print is line art or a logo rather than a photo, then true one-bit black and white is the correct target and prints crisp.
Which method should you use?
Match the method to your goal. For a fast look on the device in your hand, use the phone or Preview. For a considered photo, use a Black and White adjustment layer. For something already inside a document, use Office. Here is the trade in one view.
| Method | Cost | Control | Reversible |
|---|---|---|---|
| Phone Photos app | Free | Low, one filter or slider | Yes, saves a copy |
| Mac Preview or GIMP | Free | Low to medium | Yes, if you keep the original |
| Photoshop Grayscale mode | Paid | None, one fixed mix | No, discards color on save |
| Black and White adjustment | Paid | Full, per color | Yes, non-destructive |
| Office or Canva | Free to freemium | Low to medium | Yes |
The pattern is simple: free tools give you a fast, low-control result that is reversible as long as you keep the original, while the paid adjustment layer is the only route that combines full control with non-destructive editing. Grayscale mode is the one genuinely destructive option, so reach for it only when you are certain and working on a copy.
Does our tool convert images to black and white?
No, and it is better to say so than to send you in circles. This tool compresses and converts between JPG, PNG, WebP, and AVIF, and none of that touches color saturation. Black and white is a color-space edit, not a compression or format change, so it sits outside what the tool does.
People search how to convert a color image to black and white expecting a compressor to do it, and it does not. Where it does help is around the edit, not inside it. Once you have your black and white export, if it still needs to be smaller before it goes anywhere, that is exactly the job this tool is built for: pick a format and quality and it does the rest, losslessly for PNG. Converting to black and white to save space is the wrong move, and the file-size math above is why.