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How to resize photos for email on a Mac
By Himanshu Ranjan · Updated 8 November 2026
To make photos small enough to email on a Mac, select them and run Compress › Compress under 2 MB or Compress › Compress under 1 MB in FileDial, which save smaller copies beside the originals. For a fixed size use Resize › Resize to 1080 px. Mail's attachment image size menu also helps.
Think in file size, not pixels
Email limits are about megabytes, not pixels. A phone photo can be several megabytes by itself, so five of them bounce off many size limits. You can reach a target either by lowering the pixel dimensions or by compressing harder at the same dimensions, and the best result often mixes both.
FileDial's size-target tools make this a one-step choice. You say how small each picture must be and it works until it fits.
The FileDial tools
Pick by what you need to hit. All of these write a new copy beside the original, so your full-size photo stays in your library.
- Compress › Compress under 2 MB, under 1 MB, under 500 KB and under 200 KB: fixed targets.
- Compress › Compress to size…: a target you type.
- Compress › Compress by percentage…: shrink by a share instead of a target.
- Resize › Resize to 1080 px or Resize › Resize to 50%: reduce pixel dimensions instead.
- Convert › Make uploadable: a JPG any upload form takes, date kept, location removed.
Steps
Compress each attachment, not the zipped bundle. A ZIP of JPG files barely shrinks, because JPG is already compressed. FileDial handles the whole selection in one pass.
- Select the photos in Finder.
- Hold the right Option key to open the dial, or right-click and choose Open in FileDial.
- Choose Compress, then release on Compress › Compress under 2 MB, or a smaller target.
- Attach the new copies to your email, and leave the originals in your library.
- If the message is still too big, step down to the 1 MB tool.
Mail has a built-in option
Apple Mail lets you choose an image size when you attach pictures: in a new message, the attachment size control near the header offers options such as Small, Medium, Large and Actual Size, and the option may only show when the message contains images. Exact placement varies by version, so look for it near the Subject field after attaching.
Mail's option is convenient but you cannot always see what size comes out. FileDial's result card shows the size before and after, so you know before you send.
When email is the wrong channel
Sometimes squeezing is the wrong answer. If the recipient needs print quality, or you are sending dozens of pictures, a download link or AirDrop is better than shrinking everything. FileDial's Share menu includes AirDrop, Mail and Messages, which open the sharing route for the selected files without changing them.
If you do email many photos, aim for consistency. Resize the whole batch to the same width so they look alike on arrival, and name them sensibly so the recipient can refer to number five. Rename › Rename with sequence… gives names like Holiday 001.jpg, Holiday 002.jpg.
Another option is to send a contact sheet first, as one PDF with thumbnails and file names, and let the recipient say which they want at full size. That keeps the first message small and the second one targeted.
- Print quality: link or AirDrop.
- Many photos: same size and clear names.
- Choice needed: send a contact sheet first.
Mistakes to avoid
Do not shrink the only copy of a photo. Work on copies, which FileDial does by default, and keep the full-size version for printing. Do not rely on a ZIP to reduce photo size, because JPG and HEIC are already compressed. And do not squeeze so far that faces and text become blocky, since a message nobody can read helps nobody.
Mail's own image size option is a good built-in shortcut when you are attaching to a message right now. FileDial is stronger when you want to know the resulting size before sending, when you are preparing a batch for several messages, or when you also want location removed. For very large sets, a shared link or AirDrop beats any attachment.
A quick decision guide: for a single message with two or three pictures, Mail's own size option or Compress › Compress under 2 MB is enough. For ten or more pictures, resize the whole set to one width and consider a link instead. For pictures that need printing, never shrink them for email at all. For pictures with private location, remove location whatever size you choose, since smaller files carry the same metadata unless you strip it.
Trade-offs and privacy
Very small targets cost visible quality, especially on detailed photos. If the recipient needs to print the picture, send the larger copy through a link or AirDrop instead of squeezing it. Also remember that email attachments carry metadata. Before sending family pictures to a stranger, use Privacy › Remove location.
FileDial never uploads your files, and it works offline until you actually press send in Mail.
Questions
How small should photos be for email?
It depends on your provider's attachment limit and how many pictures you send. As a practical approach, aim for one or two megabytes each, or less if you attach many. FileDial offers Compress under 2 MB and 1 MB presets to hit those targets in one step.
Is it better to resize or compress?
Both reduce size. Resizing lowers pixel dimensions, which is fine for screen viewing. Compressing keeps dimensions and removes detail. For email, a target-size tool such as Compress › Compress under 1 MB handles the balance for you, and the result card shows what changed.
Will the original photo be kept?
Yes. FileDial saves the smaller version as a new file beside the original, and the original is not changed unless a tool says so up front. Send the smaller copy and keep the full-resolution file. Because the smaller version is a separate file, the full-resolution original stays available for printing or a later link share.
Why does zipping photos not help?
JPG and HEIC are already compressed, so a ZIP gains very little. Compress or resize the pictures themselves instead. A ZIP is still useful for sending many files as one attachment. Several attachments add together, so check the total message size against your provider's limit, not just each file.