how to reduce image size for email
modern phone cameras take beautiful photos, but "beautiful" often means 5-10mb per image. most email providers have attachment limits, and even when they don't, huge images are annoying to receive. here's how to make them smaller without making them look worse.
why email images need to be small
most email providers have attachment size limits. gmail allows attachments up to 25mb total per email. outlook allows 20mb. yahoo mail allows 25mb. these limits sound generous, but a few modern smartphone photos can easily exceed them.
even when you're under the limit, large images cause real problems. they take longer to send and receive. they eat mobile data for recipients who don't have wifi. they fill up inboxes quickly. and some corporate email systems have much stricter limits than the major consumer providers.
the goal isn't to make images as small as possible regardless of quality. it's to find the size where the image looks good enough for the context, whether that's a casual photo to a friend or a professional image for a client.
what actually determines file size
two things control how large an image file is: its dimensions (the width and height in pixels) and its compression (how efficiently the image data is stored). both matter, and both can be reduced.
dimensions. a photo from a modern smartphone might be 4000x3000 pixels. on a standard laptop screen at normal zoom, you'd only see about 1920x1080 pixels at most. the extra pixels are just making the file larger without adding any visible detail.
resizing a 4000x3000 photo to 1920x1440 reduces the total pixel count by more than 50%, which reduces the file size similarly before compression even comes into play.
the fastest approach: convert to jpg with lower quality
if your image is a photograph saved as png, the single most effective thing you can do is convert it to jpg. png is lossless, which is great for quality but terrible for file size with photos. a png photograph might be 8mb while the same photo as jpg at 80% quality is 600kb and looks identical on screen.
if your image is already jpg, you can re-save it at a lower quality setting. going from 95% quality (where most cameras save) to 80% quality typically cuts file size by 40-60% with no visible quality difference at normal viewing sizes.
for email purposes, 75-85% jpg quality is plenty. the recipient is viewing it on a screen, not printing it on a billboard.
target sizes for email images
casual photos to friends and family
under 1mb per image is plenty. most people can't tell the difference between a 200kb and 2mb jpg on a phone screen. convert to jpg at 75-80% quality.
professional photos to clients
under 2mb per image. you want them to look good, but 10mb originals are unnecessary. jpg at 85% quality is indistinguishable from the original on screen.
multiple images in one email
aim for a total attachment size under 10mb to stay safely within all email provider limits. if you need to send more, consider a file sharing link instead.
images for printing
if the recipient needs to print the image at full quality, email is the wrong tool. use a file sharing service that can handle large files, or a usb drive. don't sacrifice quality that will matter for print just to fit in an email.
what format to use for email images
jpg is the safest choice for email. every email client displays jpg images without issues. it's compact and universally supported.
png is fine for logos and graphics, but avoid it for photographs because the files are much larger than necessary.
webp is more efficient than jpg, but some email clients don't display webp images inline. stick with jpg for email unless you know the recipient's setup supports webp.
heic is the default format on iphones and it's not supported everywhere. if you're sending photos from an iphone to someone who might not have a modern apple device, convert heic to jpg first.
converting without sending your photos to a server
a lot of image compression tools online require you to upload your photos to their servers, which means your personal photos are temporarily stored on someone else's computer. for family photos or anything private, this isn't great.
cozyconvert handles everything in your browser. your photos are compressed locally using the canvas api and never transmitted anywhere. you can compress personal photos, medical images, legal documents, anything, with complete privacy. convert up to 10 images at once and download them immediately.
reduce image file size for email, files never leave your device
try cozyconvert, it's free