How to compress photos for email (under Gmail's 25 MB limit)

If you've ever tried to email a photo straight off your phone or camera and seen "attachment too large," you're hitting a hard cap your email provider sets on outgoing files. The number is lower than people think — Gmail caps at 25 MB per email, Outlook and iCloud at 20 MB, some corporate servers at 10 MB. And here's the wrinkle: those caps apply to the encoded attachment, not the raw file, which makes the effective limit about a third smaller than the headline number.

Below is the shortest path from a too-large photo to one your email client will actually send.

The 60-second version

1. Open the Unfuss compressor in your browser.
2. Drop your photo onto the drop zone.
3. Leave quality at 75% (the default).
4. Click Download.
5. Attach the new file instead of the original.

That's it. The compressor runs inside your browser tab — your photo never gets uploaded anywhere. Skip the rest of this article unless you want to understand the numbers.

Why your email said the file was too large

Email attachments are encoded in a format called MIME, which inflates the file roughly 33% during transit. So a 25 MB photo on disk becomes about 33 MB on the wire, and Gmail rejects it. Practical targets:

If you're not sure which limit applies, aim for under 7 MB and the email will go through anywhere.

What the quality slider actually does

JPEG (and WebP) compression works by throwing away data your eye can't easily see. The quality slider tells the encoder how aggressively to do that:

• 95–100% — visually lossless. File savings are modest (10–30%).
• 80–90% — the sweet spot for high-fidelity photos. You can usually save 50–70% of the file size with no visible difference.
• 70–80% — the default. Best balance for screen viewing. Typically 70–90% smaller than the original.
• 50–70% — visibly compressed if you look closely. Fine for thumbnails, bad for the photo you're actually sending.
• Below 50% — visible blockiness. Avoid.

For email, 75% quality is the right answer in almost every case. It's where the smallest file size meets the cleanest image.

What about the max-dimension slider?

A photo straight off a modern iPhone or DSLR is typically 4,000+ pixels wide. Almost no email client or screen actually displays an image that big — it gets shrunk to fit your recipient's window or app. So you're paying for resolution they'll never see.

Cap the longest side at 2,000 pixels and you usually cut file size by another 50% on top of the quality reduction, with no visible loss on any normal viewing surface. The Unfuss compressor does this automatically with the "Max dimension" control.

For prints, leave the dimension slider at 4,000 px. For email or web, 2,000 px is the right cap.

When JPEG isn't the answer

JPEG is perfect for photographs — natural lighting, smooth gradients, lots of colour variation. It struggles with three things:

• Screenshots with sharp text and solid colour areas. JPEG compresses the colour transitions and the text looks fuzzy. Use PNG instead.
• Logos and graphics with transparency. JPEG doesn't support transparency. Use PNG, or WebP if the recipient is on a modern browser/client.
• Anything you'll print at large sizes. Compression artefacts show up at scale. Use PNG or keep the original JPEG at 95% quality.

If you're sending photos of holidays, food, people, or anything taken with a real camera, JPEG at 75% quality is the right call almost every time.

How to confirm nothing was uploaded

Unfuss runs entirely in your browser. If you want to verify rather than take our word for it:

1. Open the compressor page.
2. Open your browser's developer tools (Cmd/Ctrl + Shift + I).
3. Click the Network tab. Clear the existing entries.
4. Drop a photo onto the compressor.
5. Watch the Network panel during compression.

You'll see zero outbound network requests. The compressed file appears in your downloads folder. You can disconnect from the internet entirely after the page loads and the tool will keep working.

What about multiple photos at once

Drop several files onto the compressor at the same time and they all get processed in parallel. You can either download them one by one or click Download all as ZIP to grab the lot in one go. Useful for sending a batch of holiday photos — instead of attaching ten 8 MB originals (one per email if you're unlucky), you get one ZIP that's a fraction of the size.

Quick reference

• Default quality: 75%
• Default max dimension: 2,000 px
• Aim for files under: 7 MB to land anywhere; 15 MB for consumer accounts
• Format: JPEG for photos, PNG for screenshots/logos, WebP if recipient runs a modern client
• Multiple files: drop them all at once and ZIP-download