A single photo from a modern phone is 3–8 MB, and a 48-megapixel iPhone shot can exceed 10 MB. Attach a handful to an email and you'll hit the wall fast: Gmail caps messages at 25 MB, Outlook.com at 20 MB, and many corporate mail servers reject anything over 10 MB. On the web, oversized images are the single most common reason pages load slowly.
The fix is almost never 'use a worse photo.' It's understanding the two levers — pixel dimensions and compression quality — and pulling the right one. Done properly, you can shrink a photo by 90% with no visible difference at the size people actually view it.
The two levers: resize and compress
Resizing reduces the number of pixels. A 4000×3000 photo has 12 million pixels, but an email preview or a blog column displays at most around 2 million. Downscaling to 1600 pixels wide throws away detail no one was going to see — and file size scales roughly with pixel count, so halving each dimension cuts the file by about 75%.
Compression reduces the bytes per pixel. JPEG and WebP quality settings control how aggressively imperceptible detail is discarded. The relationship isn't linear: dropping JPEG quality from 100 to 85 often halves the file with no visible change, while dropping from 85 to 60 saves less and starts showing artifacts. Quality 80–85 is the widely used sweet spot for photos.
Use both, in that order
Resize first, then compress. Compressing a needlessly huge image wastes its byte budget on pixels nobody sees. A 1600px-wide photo at quality 85 will look better and be smaller than a 4000px photo crushed to quality 50.
What sizes to aim for
| Use case | Longest edge | Quality | Typical result |
|---|---|---|---|
| Email attachment (viewing) | 1600–2048 px | JPEG 80–85 | 200–500 KB per photo |
| Email attachment (recipient may print) | 2500–3000 px | JPEG 85 | 0.8–1.5 MB |
| Website hero / full-width image | 1920–2400 px | WebP 75–82 | 150–400 KB |
| Blog inline image | 1200–1600 px | WebP 75–80 | 60–200 KB |
| Thumbnail / avatar | 200–400 px | WebP 70–80 | 5–30 KB |
For email specifically: staying near 300–500 KB per photo means you can attach a dozen without approaching Gmail's 25 MB ceiling, and recipients on mobile connections will thank you. If someone genuinely needs the full-resolution original — for printing or editing — send a link via a file-sharing service instead of fighting attachment limits.
For the web: image weight directly affects Largest Contentful Paint, one of Google's Core Web Vitals that factors into search ranking. As a rule of thumb, no single image on a page should exceed ~300 KB, and format choice helps as much as compression — WebP is typically 25–34% smaller than JPEG at comparable quality.
Compress images in your browser (no install)
- 1
Open FileMorf's image compressor
It runs entirely in your browser using Web Workers — your photos are processed on your own device and never uploaded.
- 2
Drop in your images
Batch compression works: add a whole folder of photos destined for one email or page.
- 3
Set your target
Choose maximum dimensions and quality. For email, 1920px at quality 80 is a reliable default that keeps most phone photos under 500 KB.
- 4
Download and compare
Check the before/after sizes, spot-check one image at full zoom, and download the batch as a ZIP.
Built-in alternatives on each platform
Your OS and email client can do some of this without any tool — worth knowing, with their limits:
- macOS Preview: Tools → Adjust Size to resize, and a quality slider when exporting as JPEG. Solid for single images; no batch quality control.
- Windows Photos: the Resize option offers preset dimensions. Fine for quick one-offs, minimal control over compression.
- Apple Mail and iOS: when you email photos, Mail offers Small/Medium/Large/Actual Size. Convenient, but you can't see the resulting quality before sending.
- Gmail: automatically converts oversized attachments to a Google Drive link rather than compressing — which shares your original at full size.
- Squoosh (web app by Google): excellent single-image compressor with format comparisons; processes locally like FileMorf, but one image at a time.
Mistakes that waste quality or bytes
- Compressing screenshots as JPEG: text gets fuzzy halos. Screenshots and UI images should be PNG (or lossless WebP) — see our PNG vs JPG guide.
- Re-compressing already-compressed images repeatedly: each lossy save degrades quality further (generation loss). Keep an original; derive compressed copies from it.
- Upscaling then compressing: enlarging a small image adds bytes but no detail. Resize only downward.
- Forgetting metadata: photos carry EXIF data including capture time and often GPS location. Stripping it saves a little space and, more importantly, avoids leaking where the photo was taken. Most compression tools (FileMorf included) strip or let you strip EXIF.
- Sending the original 'just to be safe': if the recipient views on a laptop screen, anything beyond ~2000 px wide is invisible surplus.
Compress images free
Batch resize and compress photos in your browser — private, instant, and free with no signup.
Frequently asked questions
How much can I compress a photo before people notice?
For typical photos viewed at normal size, JPEG or WebP at quality 80–85 is visually indistinguishable from the original — usually a 60–80% size reduction from a phone camera file, more if you also resize. Artifacts become noticeable below quality ~65, first in areas of fine texture and sharp edges.
What's the maximum size for email attachments?
Gmail allows 25 MB per message, Outlook.com 20 MB, Yahoo 25 MB — and the limit applies to the whole email after encoding overhead (attachments grow ~33% in transit). Corporate mail servers often cap at 10 MB. Keeping photos to a few hundred KB each avoids all of these limits.
Should I use WebP for email?
Not for attachments — some email clients still won't preview WebP inline, and recipients may not know how to open it. Use JPEG for email and save WebP for websites you control, where its 25–34% size advantage pays off.
Is it safe to compress private photos with an online tool?
Check where the processing happens. FileMorf compresses images client-side in your browser via Web Workers, so files never leave your device. Upload-based compressors are fine for public images but a poor choice for personal photos or anything under NDA.
Keep Reading
WebP vs JPG: Which Should You Use?
WebP files are typically 25–34% smaller than JPEGs at the same quality — but JPG still wins in some situations. A practical comparison with a decision table.
Read the guidePNG vs JPG: When Each Format Wins
PNG is lossless and supports transparency; JPG makes photos dramatically smaller. Learn exactly which format to use for screenshots, photos, logos, and the web.
Read the guideHow to Convert iPhone Photos (HEIC) to JPG on Any Device
Every way to turn iPhone HEIC photos into universal JPGs — on the iPhone itself, Mac, Windows, Android, Linux, or straight in your browser with no software.
Read the guide