How do I check an image's file size?

Drop the file above. The exact size appears in kilobytes and megabytes, down to the byte, alongside the format and pixel dimensions. It is read in your browser, so even private files never leave your device.

What's the difference between file size and image size?

File size is how much storage the file takes, measured in KB or MB. Image size usually means the pixel dimensions, like 1920 × 1080. They are related but not the same: heavy compression can shrink the file size a lot while the pixel dimensions stay identical. This checker shows both so there is no ambiguity.

Why is my image so large in KB or MB?

File size grows with pixel count, with low compression, and with format. A lossless PNG photo is often several times larger than the same photo as a JPG. A 12-megapixel image saved at full quality can easily exceed 5 MB. If the file is too heavy, compressing or converting it usually brings it down sharply.

How do I get an image under a specific KB limit?

Use a target-size compressor. Upload forms often cap photos at 100 KB, 200 KB or 1 MB, and a target tool re-encodes the image to land just under that limit while keeping it as sharp as possible. Checking the current size first tells you how much you need to cut.

Does a bigger file mean better quality?

Not reliably. Past a point, extra file size is wasted bytes from inefficient compression, not visible detail. A well-compressed image can look identical to one twice its size. The aim is the smallest file that still looks right for its use.

Is my file uploaded to check its size?

No. The size, format and dimensions are read locally in your browser. Nothing is sent to a server, which you can confirm in the Network panel.

Image Size Checker

Check image file size in KB and MB

Drop an image to see its exact file size in kilobytes, megabytes and bytes, along with the format and pixel dimensions. It is read in your browser, so the file is never uploaded, which is handy before you hit an upload limit.

Drop an image here, or click to choose

JPG, PNG, WebP, GIF, AVIF, BMP, TIFF, HEIC. Read entirely in your browser.

Files never leave your device
Runs in your browser
Free, no signup

How it works

1
Drop an image
Add one file or several. The size, format and dimensions are read in your browser instantly, with no upload.
2
Read the file size
See the exact size in KB and MB, down to the byte, next to the pixel dimensions and the format.
3
Shrink it if needed
If it is over a form's limit, compress to a target KB, convert the format, or resize to bring the size down.

What the size checker shows

Exact size, three ways

The file size in kilobytes, megabytes and the raw byte count, so it matches whatever unit an upload form or email limit uses.

Size and pixels together

File size sits beside the pixel dimensions and format, making it obvious whether a heavy file is heavy from its size, its compression, or its format.

Nothing uploaded

The file is measured in your browser. It never touches a server, so you can check personal documents and work files safely.

Where this helps

Forms

Before an upload limit

Portals cap photos at 100 KB, 200 KB or 1 MB. Check the current size first so you know whether you can upload as-is or need to compress.

Sharing

Email and chat attachments

Email and messaging apps reject oversized attachments. A quick size check tells you if a photo will go through or needs shrinking.

Web

Speeding up a web page

Heavy images are the most common cause of slow pages. Check which files are largest, then compress or resize the worst offenders.

Workflow

Auditing a folder of images

Drop a batch to compare file sizes side by side and find the bloated files worth optimising first.

Tips that help

1
KB is not the same as pixels
A small file in KB can still have large pixel dimensions, and vice versa. Read both numbers, since they answer different questions.
2
Format is the biggest lever
A PNG photo is often several times heavier than the same photo as JPG or WebP. Converting the format can cut size before touching quality.
3
Target the exact limit
When a form states a KB cap, compress to that target rather than guessing a quality level. It lands just under the limit and keeps the most detail.
4
Resize oversized photos
If a file is far larger in pixels than it needs to be, resizing down shrinks the dimensions and the file size in one step.

Image file size: what KB and MB really measure, and how to control them

File size is the number upload forms, email clients and page-speed tools care about most, yet it is widely misread as a stand-in for quality or for pixel dimensions. It is neither. This guide explains what kilobytes and megabytes actually count, why two images of the same dimensions can weigh very differently, and how to bring a file under a limit without wrecking how it looks. This checker reads the exact size in your browser, with no upload.

File size counts bytes, not pixels or quality

The file size is simply how many bytes the encoded image occupies on disk, reported in kilobytes (1 KB ≈ 1024 bytes) or megabytes. It is what a form means by a '200 KB limit' and what an email means by a '25 MB attachment cap'.

It is not the pixel dimensions. A 1920 × 1080 image might be 80 KB or 4 MB depending only on how it is compressed and stored. And it is not quality in any direct sense, since a leaner file can look identical to a bloated one if the compression is good.

Three things drive the size: how many pixels there are, how aggressively the image is compressed, and which format encodes it. Change any of those and the byte count moves, often dramatically.

Why the same picture can weigh very differently

Format is the biggest lever. A photograph stored as lossless PNG can be three to five times heavier than the same photo as a JPG, because PNG keeps every pixel exact while JPG discards detail the eye barely notices. WebP and AVIF go smaller still at similar visual quality.

Compression level is the next lever. Within JPG or WebP, a quality setting decides how much is thrown away; dropping from maximum to a sensible mid-quality often halves the file with no obvious difference. Past that, artefacts start to show.

Pixel count is the third. Resizing a 6000 px photo down to the 1500 px a web page actually displays cuts the byte count steeply, because there are far fewer pixels to store. Knowing the current size and dimensions tells you which lever to pull.

Bringing a file under a limit

If a portal caps uploads at an exact figure, a compress-to-target tool is the precise fix: it re-encodes the image to land just below 100 KB, 200 KB, 1 MB, or whatever the form states, keeping quality as high as the limit allows.

If the file is heavy mainly because it is a PNG photo, converting it to JPG or to WebP can shrink it sharply on its own, before any quality is sacrificed.

And if the image is simply far larger in pixels than it needs to be, resizing it down reduces both the dimensions and the file size in one step. Reading the current size here tells you how far you have to go.

Frequently asked questions

Honest answers to what people ask before using this tool.

Check image file size in KB and MB

How it works

Drop an image

Read the file size

Shrink it if needed