How to Reduce Image File Size | What to Do When You Hit an Upload Limit
“File size too large” stops you submitting a form or attaching an image to an email. What works in that situation is two things: changing the format and the quality setting. This guide explains how far to lower each to reach a given size, and the order to work in so the image still looks good, with steps that run entirely in your browser.
Three reasons an image file is large
Before reducing the size, working out why the image is large saves you from lowering the quality unnecessarily. There are really only three causes.
- 1. Too many pixels: phone photos are around 4000 × 3000 pixels, often far more than you need for display
- 2. The wrong format: saving a photo as PNG can make it several times larger than JPEG
- 3. A quality setting that is too high: quality 100 and quality 80 look almost the same, but the file sizes differ a lot
Of these, 2 and 3 can be fixed with a converter in tens of seconds. Reducing 1 (the pixel count) is resizing, a separate job from conversion. The efficient order is to try 2 and 3 first and, if that's not enough, reduce the width and height in pixels with the Image Resize tool. If the image is only for display, shrinking the long edge to around 1600 px causes no problems.
When changing the format alone shrinks the file
Changing the format causes the least loss and has the biggest effect. Especially when “screenshots or photos have been saved as PNG”, changing the format alone cuts the size dramatically.
| Current state | Recommended format | Expected effect |
|---|---|---|
| A photo saved as PNG | JPEG or WebP | Large reduction. PNG compresses photos poorly, so the gain is easy to get |
| A heavy PNG screenshot | WebP | Smaller while keeping text from blurring |
| JPEG but still too large | WebP | Often smaller again for the same look |
| An illustration or logo saved as JPEG | PNG | The size may go up, but the fuzzy edges disappear |
| An image that needs transparency | PNG or WebP | Can't use JPEG (transparent areas are filled with white) |
The rule of thumb is simple. Images with smooth colour changes, like photos, suit JPEG or WebP; images with flat colours and sharp edges, like logos and diagrams, suit PNG or WebP. If in doubt, try WebP: in most cases it comes out smallest.
How far you can lower the quality
JPEG and WebP have a quality setting. The slider goes from 10 to 100 and starts at 90. Lower values make smaller files, but go too low and noise appears around edges.
| Quality | How it looks | Good for |
|---|---|---|
| 100 | Practically no loss. Little size reduction | Printing, material you will edit later |
| 90 (default) | Hard to see a difference even when zoomed in | General use. Start here |
| 80 | Almost indistinguishable at actual size | Web pages, pasting into documents |
| 70 | Slight blotchiness starts to appear in flat areas | Thumbnails, social media posts |
| 50 or less | Noise around edges and text becomes noticeable | A last resort under strict size limits |
In practice, the safe approach is to try 90, then 80, then 70, and stop as soon as you reach your target size. Images containing text (screenshots, charts) show degradation easily, so we recommend not going below 70.
Converting in your browser and checking the file size
No app to install and no sign-up. Conversion happens inside your browser, and images are never sent to a server.
- 1
Choose an image
Load the image by choosing a file or dragging and dropping it. Once loaded, the original format and size are shown.
- 2
Choose the output format
Pick PNG, JPEG or WebP. Trying WebP first shows you roughly how small the file can get, which makes the decision easier.
- 3
Adjust the quality
When you choose JPEG or WebP, the quality slider appears. Start from the default of 90 and lower it as needed.
- 4
Convert and compare sizes
Press the convert button to see the converted file size and how many bytes you saved compared with the original. If you haven't reached your target, lower the quality and convert again. If the size went up, it shows “increased”, so reconsider whether you picked the right format.
- 5
Download
When you're happy with the size, download it. The file keeps its original name; only the extension changes to the new format's.
Typical size limits by destination
These are rough guides to “how small is small enough”. Each service's own instructions take priority for exact limits, but having a rough sense speeds things up.
| Use | Typical limit | Size to aim for |
|---|---|---|
| Email attachments (total) | Often rejected at around 10 MB | 1 MB or less per image |
| Application and registration forms | Often 2–5 MB | Half the stated limit or less |
| Images on a web page | No hard limit, but directly affects loading speed | 200–500 KB |
| Social media profile pictures | A few MB | 500 KB or less is plenty |
| Pasting into chat | Tens of MB | Fine to prioritise quality |
An easy thing to miss is a form that specifies the format. If it says “JPEG only” or “PNG format”, a WebP file won't be accepted however small it is. Check both the size and the format before converting.
Five things to check before you shrink an image
- Keep the original: once you lower the quality, you can't get it back. Store the pre-conversion file separately
- Don't recompress repeatedly: converting a JPEG over and over adds loss each time. Always convert from the original
- Check for transparency: if you need transparency, you can't choose JPEG
- Check the required format: some destinations still don't accept WebP
- Check whether there is text: screenshots and charts become hard to read if you lower the quality too far
The second point, “don't recompress repeatedly”, is the one most often overlooked. If you convert an image saved at quality 80 again at quality 80, the loss doesn't stay at 80; it is applied twice. When you redo a conversion, always start again from the original file. For which format makes a file lighter, see the differences between PNG, JPEG and WebP, which sums up each format's characteristics.
FAQ
- Are images uploaded to a server?
- No. Loading and conversion both happen inside your browser, and image data is never sent anywhere. Nothing remains once you close the page.
- Can I also reduce the resolution (pixel count)?
- This converter changes only the format and quality and keeps the original resolution. To reduce the pixel count, use a tool with a resize function alongside it.
- Can WebP be used everywhere?
- Major browsers support it, but some submission forms and apps still don't accept it. If the destination specifies a format, choose JPEG or PNG.
- I converted to PNG and the file got bigger
- PNG is a lossless format, so turning a photo into PNG can increase its size. If your goal is to make a photo smaller, choose JPEG or WebP.
- Can I convert several images at once?
- At the moment it converts one image at a time. If you have many, process the most important ones first.
Tools in this article
Related articles
Inches to cm: How to Read TV, Bike Wheel and Jeans Sizes
A TV is “55 inches,” a bike is “26 inches,” and jeans are “W30.” They all use inches, but each one measures something different, so converting the number straight to centimeters doesn't always give you the dimension you actually need. This guide covers the 1 inch = 2.54 cm conversion and a mental-math shortcut, what the inch figure means for each kind of product, and how inches relate to Japan's traditional shaku and sun units.
Read article →How to Remove Location Data from Photos: Check EXIF Before Posting to Social Media
Photos taken with a smartphone may contain the latitude and longitude of where they were taken. This guide explains what is recorded in a photo, which ways of sharing keep that data and which strip it, and how to check and remove location data on each type of device.
Read article →Image Resolution vs. DPI: How Many Pixels You Need for Web and Print
When a print shop tells you to “submit at 350 dpi,” it’s hard to tell whether the image you have meets the requirement. In fact, the only real substance of an image is its pixel count; dpi is just an instruction for how many centimeters or inches to print those pixels across. This guide covers the relationship between resolution, dpi, and pixels, how to calculate the pixels you need from a paper size, and why dpi has nothing to do with how images look on the web.
Read article →