How small should each image be to fit an attachment limit?

Most providers cap a message around 20 to 25 MB including all attachments, so budget about 10 MB for images after leaving room for the document or spreadsheet riding along. Five photos at 400 KB each fit comfortably; fifteen at 1.5 MB each will bounce. Check your provider's exact limit, then aim a third under it.

Will compressing make the images look bad if I print them?

If the email is the only destination, no — at 80 to 85 percent quality the result looks the same on a screen. Printing is different: heavy compression shows as blocky edges around fine detail, and any resizing below 300 DPI at the final print size makes the image soft. Keep the originals if the photos might ever be printed.

Should I send photos as JPG or PNG?

JPG for photographs, because PNG's lossless compression keeps every pixel and produces a file three to five times larger for no visible benefit on a photo. Screenshots with text are the exception — those stay sharp as PNG, or as JPG at 90 percent or higher.

Are my images uploaded when I compress them?

No. The compression runs inside your browser using its own image encoder. Files are read from your machine, converted, and offered back to you as a download — nothing is transmitted to a server or kept afterwards.

Compress Images for Email Attachments

Most email providers limit attachments to 25MB (Gmail) or 20MB (Outlook). A single photo from a modern phone can be 5-12MB. Here is how to shrink images so they actually send.

Why Images Are So Large

Modern phones capture 12-48 megapixel photos. A single uncompressed JPEG from an iPhone 15 is roughly 5-8MB. PNG screenshots of detailed interfaces can hit 3-5MB. These sizes quickly exceed email limits when you attach more than one file.

What I Tested

I took a 6.2MB JPEG photo (4032×3024 pixels, shot on a phone) and a 4.1MB PNG screenshot of a spreadsheet. I used the Image Compressor at three quality settings and recorded the results.

Results at Different Quality Settings

• 90% quality: JPEG dropped to 1.8MB (71% reduction). PNG dropped to 1.2MB (71% reduction). Visually identical to the original on a standard monitor.

• 70% quality: JPEG dropped to 820KB (87% reduction). PNG dropped to 640KB (84% reduction). Slight softening visible on zoom to 200%, but fine for email previews.

• 50% quality: JPEG dropped to 410KB (93% reduction). PNG dropped to 310KB (92% reduction). Noticeable compression artifacts around text and sharp edges.

For email, 70-80% quality is the sweet spot. The files shrink dramatically while remaining perfectly readable on screen.

How to Compress

(1) Open the Image Compressor. (2) Click 'Select Images' and choose up to 10 files. (3) Set the quality slider to 75%. (4) Click 'Compress'. (5) Download the compressed files individually or as a ZIP.

One Limitation

The tool uses lossy compression for JPEG and WebP. PNG compression uses color quantization, which reduces the color palette. For photos saved as PNG, you may see slight color banding in gradients at lower quality settings. If color accuracy is critical (medical imaging, photography portfolios), keep quality above 85%.

Common Mistake

Users often compress the already-compressed JPEG again, expecting further gains. A second pass at the same quality level produces almost no size reduction because the data was already discarded. If you need smaller files, lower the quality slider or resize the dimensions first using the Image Resizer.

How It Compares

TinyPNG compresses well but requires uploading images to their server and limits free use to 500 images per month. Squoosh (by Google) runs in-browser like ours but handles one image at a time with no batch support. Our tool supports batch compression of up to 10 files with no upload, no account, and no image count limits.

Privacy

Your photos stay on your device: the compressor reads them with Canvas and writes the smaller file locally, so nothing is ever uploaded and nobody at FreeDigitalToolkit can open your files.

Next Step

If you need to compress images to a specific file size (for example, exactly 100KB for a job application portal), use the Compress to Size tool instead. It targets a file size and finds the best quality automatically.

Building a Size Budget for One Message

Start from the limit, not from the photos. If your provider allows 25 MB and you are attaching a 2 MB document, the images get 23 MB — and because most providers calculate the size after encoding, allow roughly a third extra for the base64 wrapper that email adds to every attachment. In practice a safe budget is 15 MB of actual image data.

Then work backwards per photo: a holiday album of ten shots at 700 KB each is 7 MB and sends without complaint, while the same ten at 3 MB each needs a cloud link instead. If a set will not fit, either lower the quality to 80 percent or resize the long edge to 1600 pixels — for screen viewing that change is invisible and it cuts the file far more than another notch on the quality slider.

Compressing a Batch Without Losing the Original

Compress into a new folder rather than over the files you have. The original PNGs and camera JPEGs are what you would use for printing, reprinting or cropping later, and once a photo has been recompressed a second time the artifacts start to show.

Name the output set as well — IMG_1234-compressed.jpg or similar — so nobody reattaches the 8 MB original by mistake a week later. If the same images are going out repeatedly, keep the compressed copies as the shareable set and treat the originals as the archive.