What is the difference between image dimensions and file size?

Image dimensions are the pixel width and height. File size is the storage used by the file, measured in KB or MB. Two images can have the same dimensions but different file sizes because format, compression, transparency, metadata, and visual detail affect storage.

How is the image aspect ratio calculated?

The width and height are divided by their greatest common divisor. For example, 1920 × 1080 simplifies to 16:9, while 1080 × 1350 simplifies to 4:5.

How are image megapixels calculated?

Multiply pixel width by pixel height, then divide by one million. A 4000 × 3000 image contains 12,000,000 pixels, or 12 megapixels.

Does checking an image upload or change it?

No. The browser reads the selected file locally to obtain its intrinsic dimensions. This checker does not upload, resize, recompress, or save the image.

Why can’t the checker read my image?

Browser format support varies. A file may also be incomplete, mislabeled, corrupted, larger than the checker limit, or encoded with a feature the current browser cannot decode. Try the original file in an up-to-date browser.

Can I use the dimensions to predict print size?

Yes, once you also choose a target pixels-per-inch value. Use the pixel-to-print size calculator to divide width and height by PPI and compare the result with your intended physical print dimensions.

Image Dimensions Checker

Choose an image to read its intrinsic pixel dimensions, simplified aspect ratio, megapixel count, orientation, format, and file size. The check runs locally in your browser and does not change the file.

How to check the dimensions of an image?

1
Step 1: Choose an image
Select an image from your device or drag it into the checker. Use a format that your browser can display.
2
Step 2: Read the image details
The checker decodes the file locally and reports its intrinsic width and height in pixels, aspect ratio, megapixels, orientation, format, and file size.
3
Step 3: Use the measurements
Compare the results with the requirements for your website, print project, marketplace, or social platform. The original file is not changed.

Reviews

Loved by Instasize Creators

4.7

| 325K App Store ratings

One of my go-to apps

Great app for filtering photos and even greater app for sizing pictures for not only posts but story photos as well... love this app I mainly use insta size for all my posts now ;)

@beachxbunny

Fast and Straightforward

Resizing photos for social media should be a cinch, but most editing programs are a pain to use. Of the dozen I’ve used, Instasize is the fastest, easiest and most consistent...

@Soho Brad

Great Sizes

Perfect app for the exact social media picture sizes. Love it. I use it daily. & I like the premade options they give you for different social medias!

@Baby24doll

I love instasize

Its the best app. for sizing photos to fit for Instagram or other forms of social media. You can also edit photos and create collages with multiple photos. It’s had been my friend for several years!

@Jay town

Always helpful

Always helpful when needing to resize photos

@Leobaby96

Huge fan

I love this app. Makes posting all types of photos. Love how it makes them fit on different formats

@Nicola Bella

I’ve been using for years. Can’t work without it.

I use this app everyday to perfectly resize images for all of my social media platforms

@The Flywire

LOVE

This app saved the day for me! I’m finally able to resize my photos for IG....effortlessly

@Tamrinaann

Great App

We use this App weekly to resize pics for social media posts. Very user friendly, easy to use program when you want to get in and out quickly...

@cle957

One of my go-to apps

Great app for filtering photos and even greater app for sizing pictures for not only posts but story photos as well... love this app I mainly use insta size for all my posts now ;)

@beachxbunny

Fast and Straightforward

Resizing photos for social media should be a cinch, but most editing programs are a pain to use. Of the dozen I’ve used, Instasize is the fastest, easiest and most consistent...

@Soho Brad

Great Sizes

Perfect app for the exact social media picture sizes. Love it. I use it daily. & I like the premade options they give you for different social medias!

@Baby24doll

I love instasize

@Jay town

Always helpful

Always helpful when needing to resize photos

@Leobaby96

Huge fan

I love this app. Makes posting all types of photos. Love how it makes them fit on different formats

@Nicola Bella

I’ve been using for years. Can’t work without it.

I use this app everyday to perfectly resize images for all of my social media platforms

@The Flywire

LOVE

This app saved the day for me! I’m finally able to resize my photos for IG....effortlessly

@Tamrinaann

Great App

We use this App weekly to resize pics for social media posts. Very user friendly, easy to use program when you want to get in and out quickly...

@cle957

One of my go-to apps

Great app for filtering photos and even greater app for sizing pictures for not only posts but story photos as well... love this app I mainly use insta size for all my posts now ;)

@beachxbunny

Fast and Straightforward

Resizing photos for social media should be a cinch, but most editing programs are a pain to use. Of the dozen I’ve used, Instasize is the fastest, easiest and most consistent...

@Soho Brad

Great Sizes

Perfect app for the exact social media picture sizes. Love it. I use it daily. & I like the premade options they give you for different social medias!

@Baby24doll

I love instasize

@Jay town

Always helpful

Always helpful when needing to resize photos

@Leobaby96

Huge fan

I love this app. Makes posting all types of photos. Love how it makes them fit on different formats

@Nicola Bella

I’ve been using for years. Can’t work without it.

I use this app everyday to perfectly resize images for all of my social media platforms

@The Flywire

LOVE

This app saved the day for me! I’m finally able to resize my photos for IG....effortlessly

@Tamrinaann

Great App

We use this App weekly to resize pics for social media posts. Very user friendly, easy to use program when you want to get in and out quickly...

@cle957

FAQ

Image Dimensions Checker FAQ

Can't find what you're looking for? Contact support

Choose the image in this checker. Once the browser decodes it, the width and height appear in pixels, such as 1920 × 1080. These are the intrinsic dimensions stored in the file, not the size at which a website happens to display it.