A photo from a recent phone can be five to fifteen megabytes. Send a handful by email and the message bounces; post one to a form and it says the file is too large. The fix is rarely to give up quality. It is to take away only what nobody can see.
Why photos are so heavy
Two things decide a photo's file size: how many pixels it has, and how much detail is stored for each region of those pixels. A modern phone camera records twelve million pixels or more, which is far beyond what a screen, a chat window or a web form can show. Most laptop screens are about two million pixels across the entire display, so a twelve-megapixel photo is carrying six times more information than the screen can use.
That extra information is why a single picture can fill an email attachment limit. It is also the reason you can shrink a photo dramatically and still see no difference when you look at it on a screen.
Step one: make the photo the right size
Start with the pixel size, because it gives the biggest saving for the least visible cost. Decide where the photo is going and pick a size that matches. For a message or an email that people will read on a screen, about 1,600 pixels on the longest side is plenty. For a full-screen slideshow, 1,920 is enough. For a small picture on a web page, 1,000 or less will do.
On our Resize image page, choose Longest side, type the number, and drop your photos in. Portrait and landscape photos both come out right because only the longer edge is fixed and the other edge follows, so nothing is stretched. Because every photo on the page is redone when you change the number, you can try a different size on the whole batch in one go.
Step two: lower the quality a little
After the size is right, use Compress photo to save the picture again at a slightly lower quality setting. This throws away fine detail that is hard to see, such as the faint grain in a plain sky. The starting setting of about 75 percent suits most photos. Slide it left until you can just see a difference in the preview, then nudge it back to the right.
Do the steps in this order. Resizing first means the compressor is working on far fewer pixels, so you reach a small file at a higher quality setting than if you had compressed the full-size photo. People who do it the other way round often end up with blocky edges and a file that is still too large.
A quick guide to what to expect
These are rough figures, and every photo behaves a little differently, but they give you an idea of what is realistic when you follow both steps:
- A phone photo of 4 to 8 MB often falls to somewhere between 200 KB and 600 KB at 1,600 pixels wide.
- A photo with a lot of fine detail, such as leaves or a crowd, shrinks less than a photo with plain areas, such as a portrait against a wall.
- A photo that was already compressed, for example one saved from a messaging app, may not shrink much and the tool will keep your original if it cannot make it smaller.
Keep your originals
Every file we create is a new copy. Your original stays exactly as it was. That matters because compressing a photo is a one-way street: once detail is thrown away it cannot be brought back, and compressing the same file again and again makes it steadily worse. Keep the full-size originals in one folder and send the smaller copies. If you need a different size next month, start from the original, not from the small copy.
If you are collecting photos to send as a set, our Save all as one zip button gives you a single file to attach instead of a dozen separate ones.
When a photo still will not fit
If a form still refuses the file, check what it actually asks for. Some websites set a limit in kilobytes, some in pixels, and some only accept certain file types. A form that wants JPG will not take an iPhone HEIC photo, so convert it first with HEIC to JPG. A form that wants a very small file, such as 100 KB, usually needs a smaller pixel size as well as a lower quality setting: try 1,000 pixels on the longest side and then compress.
For several photos that must arrive as one document, putting them in a PDF is often easier for the person receiving them. See our Photos to PDF tool and the tip on scanning documents with a phone.