Converting Images for Email, Web, Print and Social
The right image format depends almost entirely on where the image is going. A file that is perfect on a web page is the wrong file to email, and the file you send to a print shop is wrong for both. This page works through the common destinations one at a time, says what to convert to and why, and flags the mistakes that cause rejected uploads and unhappy recipients. Everything here can be done in the free image converter, on your own device.
The one-line version: email and forms want JPG. Websites you control want WebP. Print wants a high-quality JPG at full resolution. Logos and screenshots want PNG. Social platforms will re-encode whatever you give them, so give them something good.
Email attachments
Convert to: JPG at 80 to 85% quality.
Email is the least forgiving destination, because you have no idea what the recipient is using. It might be a current phone, a decade-old desktop client, or a corporate system with its own preview renderer. JPG is the only format you can be certain will open, which is why converting an iPhone photo before sending is worth the twenty seconds it takes. Use HEIC to JPG for phone photos and PNG to JPG for oversized screenshots and exports.
Size matters as well as format. Mail providers commonly cap total message size in the range of 20 to 25 megabytes, and many corporate gateways are stricter. Several full-resolution phone photos will exceed that quickly. Dropping the quality to 80 percent and, if the photos are only going to be looked at on a screen, reducing the dimensions beforehand will comfortably fit a dozen images into one message.
One frequent annoyance: sending a folder of photos as a set of separate attachments makes them harder for the recipient to save. If you are converting a batch here, the Download all button saves them one after another, and you can then zip the folder before attaching.
Web pages you control
Convert to: WebP at 75 to 85% quality, or AVIF for the images that matter most.
When you write the markup, you choose the format, so choose the efficient one. WebP is displayed by every major current browser and typically runs 25 to 35 percent smaller than a JPG of comparable quality, which is a straightforward speed improvement across an image-heavy page. JPG to WebP handles the conversion in a couple of clicks. For hero images and anything above the fold, AVIF usually shaves off more still, at the cost of slower encoding.
Two rules keep web images honest. First, do not serve pixels nobody sees: match the dimensions to the largest display size, allowing roughly double for high-density screens. Second, do not stack lossy formats: convert from your best original rather than from a JPG that has already been squeezed once. Our guide to size versus quality goes through the arithmetic.
Screenshots, diagrams, and logos on a web page are the exception. Those want PNG or lossless WebP, because lossy compression smears exactly the sharp edges that make them readable.
Printing
Convert to: JPG at 95% quality, at the largest dimensions you have. PNG if the shop accepts it.
Print is the one destination where file size does not matter and resolution does. A screen shows a photo at roughly a hundred pixels per inch; print wants several times that, which is why an image that looks flawless on a laptop can look soft as a postcard. Never downscale for print, and never re-save at a low quality setting to "save space" on a file you are uploading once.
Format-wise, print workflows are conservative. JPG, TIFF, and PDF are the expected inputs. WebP, AVIF, and HEIC are frequently rejected, so convert an iPhone photo before uploading it to a print service. If the shop offers a color profile or paper preference, follow their guidance rather than guessing; conversion here produces standard sRGB output, which is what consumer print services expect.
Social media uploads
Convert to: JPG at 85 to 90% quality, at the platform's recommended dimensions.
Every large platform re-encodes uploads to its own format and settings, so the file you upload is not the file anyone sees. That has two consequences. It means fussing over your own compression is largely wasted effort, and it means uploading an already-degraded file is genuinely harmful, because the platform's compression is applied on top of yours and the artifacts compound. Give the platform a clean, generously sized JPG and let it do its thing.
Do check the recommended dimensions for the specific slot you are filling, since posts, stories, banners, and profile pictures all differ, and an image cropped by the platform rarely gets cropped the way you would have chosen. Transparency will not survive most upload pipelines, so if a logo needs to sit on a background, put it there yourself before uploading rather than hoping the alpha channel makes it through.
Online forms and portals
Convert to: whatever the form's accept list says, usually JPG or PNG.
Job applications, insurance claims, school portals, government services, and rental sites all tend to run on conservative software with hard rules. When an upload is refused, it is nearly always one of three things: the format is not on the list, the file is over a size cap, or the dimensions exceed a maximum. Convert to JPG or PNG to fix the first, lower the quality slider to fix the second, and resize before converting to fix the third.
Documents photographed with a phone deserve a special mention. A photo of a form or a receipt is often uploaded as a several-megabyte HEIC that the portal rejects. Converting it to JPG at 85 percent typically produces a file a fraction of the size that is still perfectly legible, and it removes the HEIC compatibility problem at the same time.
Website favicons and app icons
Convert to: ICO, from a square PNG.
The little icon in a browser tab is its own case. Start from a square PNG at 256 pixels or larger, ideally with a transparent background, and use PNG to ICO. The result is a multi-size icon file containing 16, 32, 48, and 256 pixel versions, so the browser always has a crisp one to draw. Simple, high-contrast artwork survives being shrunk to 16 pixels; detailed logos do not.
Quick reference
| Destination | Format | Quality | Watch out for |
|---|---|---|---|
| JPG | 80 to 85% | Provider size caps; HEIC attachments | |
| Your website | WebP or AVIF | 75 to 85% | Serving pixels nobody sees |
| JPG | 95% | Downscaling; unsupported formats | |
| Social | JPG | 85 to 90% | Platform re-encoding and cropping |
| Forms | JPG or PNG | 80 to 90% | Strict accept lists and size caps |
| Screenshots | PNG | Lossless | JPG smearing small text |
| Favicon | ICO | Lossless | Non-square or overly detailed source |
Common questions
What format should I use for email attachments?
JPG, at around 80 to 85 percent quality. It opens on every device without exception, and it keeps attachments small enough to pass the size limits most mail providers apply. Convert HEIC photos from an iPhone before attaching them, since many recipients cannot open HEIC.
Why does a website reject my image upload?
Usually one of three reasons: the format is not on the form's accept list, the file exceeds a size cap, or the dimensions exceed a maximum. Converting to JPG or PNG solves the first, lowering the quality setting solves the second, and resizing before converting solves the third.
What format is best for printing photos?
A high-quality JPG at 95 percent, or a PNG if the print shop accepts it and file size is not a concern. Keep the largest dimensions you have, since printing needs far more pixels than a screen does. Avoid WebP, AVIF, and HEIC unless the shop explicitly lists them.
Does it matter what format I upload to social media?
Less than people think, because platforms re-encode almost everything on upload. Give them a good-quality JPG at sensible dimensions and let their pipeline do the rest. Uploading an already heavily compressed file is what causes visible damage, since the platform then compresses it again.
Should I use WebP for images in an email?
No. Email clients are far more varied and conservative than browsers, and some will not render WebP. JPG and PNG are the safe formats for anything sent by email, whether attached or embedded in an HTML message.
Convert for your destination: open the image converter, drop in your files, choose the format from the table above, and download. Nothing is uploaded to a server.