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How to convert photos to black and white on a Mac
By Himanshu Ranjan · Updated 8 November 2026
To make photos black and white on a Mac, select them in Finder and run Adjust › Black & white in FileDial, which saves a new copy of each beside the original. Preview and Photos have their own monochrome filters for single images. Black and white works best on photos with strong contrast and clear shapes.
What black and white means here
Strictly speaking, most 'black and white' photos are grayscale: images made only of gray tones from black to white. Wikipedia separates this from one-bit black and white, which has no in-between tones. A standard 8-bit grayscale image has 256 shades.
Converting from colour has no single correct recipe. Different weightings of red, green and blue give different looks, and Wikipedia notes green contributes the most to perceived brightness in sRGB and blue the least. That is why two apps can produce visibly different monochrome versions of the same picture.
Batch convert with FileDial
Adjust › Black & white takes your selection and writes a new copy for each file beside the original. Because it makes copies, you can compare against the colour version and delete whichever you do not want.
- Select the photos in Finder.
- Hold the right Option key to open the dial, or right-click and choose Open in FileDial.
- Choose Adjust, then release on Adjust › Black & white.
- Open the new copies. Undo is available if you want to retry on a different set.
Make the result look good
Black and white removes colour as a way to separate things, so contrast and tone do the work. Photos with strong light, texture, shadow or clear shapes convert well. Flat, evenly lit scenes can look dull once the colour is gone.
If a converted copy looks flat, try Adjust › Auto enhance first or after, and Adjust › Sharpen for detail. Each tool writes its own new copy, so you can try a combination without risking the original. Enhance, then convert, tends to give a more deliberate result than converting first.
- Good candidates: portraits, architecture, street scenes, high-contrast landscapes.
- Weak candidates: pastel scenes, low-contrast fog, colourful graphics where hue carries the meaning.
- Try Adjust › Auto enhance before Black & white on dull originals.
Other ways on a Mac
Photos has black and white filters under Edit, and Preview's Markup toolbar offers colour adjustment on single files. Both are fine for one or two images and let you tweak by eye. They are less handy for a whole shoot, where a batch tool saves time. For documents rather than photos, a black and white scan is a different job, see the Scan to PDF tool in the Adjust menu.
The names and positions of Photos filters change between versions, so check in the Edit view rather than relying on a fixed path.
Print, web and archive considerations
A black and white copy is a creative choice, not a replacement. Keep the colour original as your master, because you cannot get colour back from a grayscale file. If you plan to print in black and white, check the print service's guidance on greyscale files and colour profiles, since a good print is sensitive to tone.
For the web, grayscale JPGs can be smaller than colour ones at the same dimensions, because there is less information to store, though the saving varies with the picture. Run Compress › Compress afterwards if size matters.
For documents, remember that black and white photos of paper are a different job. If your goal is a clean copy of a page, use Adjust › Scan to PDF…, which straightens document photos into a searchable PDF.
- Keep the colour original.
- Compress after converting for web use.
- Use Scan to PDF for pages of paper.
When to use something else
For one picture where you want to tweak contrast and tone by eye, the Photos app edit view or an editor with sliders gives more control than a one-step conversion. FileDial is the better fit for a consistent look across a whole folder, such as a series that must match.
Mistakes to avoid include converting poorly exposed pictures and hoping black and white will rescue them, which usually exaggerates flatness. Fix exposure first, convert second. Also avoid overwriting colour originals. The tool writes copies, so use that safety. For scans of documents, black and white is a different problem with its own tool, Adjust › Scan to PDF…
A quick decision guide: for a whole shoot that should match, use the batch tool and fix exposure first. For a single hero image, edit by eye in Photos or an editor. For documents, use Scan to PDF. For a print, ask the print service what it expects. In every case keep the colour version, since black and white is a one-way trip, and name copies so a grayscale file is never mistaken for the original colour image.
Local and non-destructive
Nothing leaves your Mac: files are never uploaded and FileDial works offline. Originals stay in colour beside the new copies.
Questions
Is black and white the same as grayscale?
In everyday use, yes, although strictly grayscale means an image made of gray tones, while pure black and white has no gray at all. Photo editors almost always produce grayscale, which holds many tones and looks like a classic black and white print.
Why do two apps give different black and white results?
Converting from colour has no single correct method, because different channel weightings change how bright each colour looks in gray. Green counts for the most perceived brightness and blue the least. Apps pick different weightings, so results differ slightly. Green carries the most weight in perceived brightness and blue the least in sRGB, so a green leaf often renders lighter than a blue sky.
Can I convert a whole folder at once?
Yes. Select all the photos and run Adjust › Black & white. FileDial saves a new copy for each, beside the original, and works in batches. You can use Undo if you decide against the whole set. If the originals are dull, run Adjust › Auto enhance first and convert afterward, since flat exposure looks flatter in gray.
Will it change my original colour photos?
No. FileDial writes new copies beside the originals and does not change them unless a tool says so up front. The result card shows what changed, and Undo is available on every result. Grayscale conversion is one-way, so keep the colour copies in case you want colour again.