Aspect Ratio Calculator
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Free online Aspect Ratio Calculator for pixel perfect video and image resizing.


Enter a Resize Width, Height or Percentage below.

OR
"Source ratio" (or "aspect ratio") refers to the proportional relationship between an image's width and height, expressed as a ratio like 16:9 or 4:3.

Aspect Ratio Calculator tool – Example 1: Resize by Percentage

Step 1 – First enter the “Source Width” and “Source Height”.
  • Example: Enter 1920 for the “Source Width” and 1080 for the “Source Height”.
  • Note the “Source Ratio” will be automatically calculated”.
Step 2 – Next you can enter the “Resize Percentage” value.
  • Example: Enter 50.
Step 3 – Now select the blue “Calculate” button. You should see the correct size calculated in the “Output Width” and “Output Height” fields.

Aspect Ratio Calculator tool – Example 2: Reize by Width Value

Step 1 – First enter the “Source Width” and “Source Height”.
  • Example: Enter 1920 for the “Source Width” and 1080 for the “Source Height”.
  • Note the “Source Ratio” will be automatically calculated”.
Step 2 – Next enter a specific width into the “Output Width” field.
  • Example: Enter 1280.
Step 3 – Now select the blue “Calculate” button. You should see the correct size calculated in the “Output Height” field.

Aspect Ratio Calculator tool – Example 3: Resize by Height Value

Step 1 – First enter the “Source Width” and “Source Height”.
  • Example: Enter 1920 for the “Source Width” and 1080 for the “Source Height”.
  • Note the “Source Ratio” will be automatically calculated”.
Step 2 – Next enter a specific height into the “Output Height” field.
  • Example: Enter 720.
Step 3 – Now select the blue “Calculate” button. You should see the correct size calculated in the “Output Width” field.

What does aspect ratio mean?

Aspect ratio is used to describes the ratio between the width and height of an image or video clip. A 1:1 aspect ratio, for example, would be a square. Having an understanding of accept ratios will help when you need to resize an image or video clip to fit a specified dimension. Using this free tool will help you to preserve the aspect ratio for both video content and images.

In most cases, aspect ratios are calculated by the width and height using pixels. For example, you probably have a TV and heard of 1080p, this is a common HD resolution that has a width of 1920 x 1080 pixels with an aspect ratio of 16:9.

In most cases, when you are editing content for a website, you are more concerned with the width of the image and this is the main constraint factor.

At DCP we use the aspect ratio tool above to calculate the height of images we add to our blog post content.

All images added to our blog post content must be a maximum of 750 pixels wide. So when I download an image from unsplash.com I need to quickly and accurately calculate the correct height for the image.

Example image from unsplash.com for Aspect Ratio Calculator

Example image from unsplash.com

Calculate Image Aspect Ratio

The original downloaded image from unsplash.com was 4240 x 2832 pixels. I know that on my blog I want the image to be a maximum width of 750 pixels. I can simply enter the following data into the aspect ratio calculator tool above:

  • Source Width = 4240
  • Source Height = 2832
  • Output Width = 750

Next, I will click the blue “Calculate” button.

Calculator Returned Results

The calculator will return the correct height value: 501 pixels Note: it would make sense to round the height to 500 pixels and crop 1 pixel from the top or bottom of the image. The image that you see above has a height of 334 pixels. We can use the aspect ratio calculator tool to calculate the correct width:

  • Source Width = 4240
  • Source Height = 2832
  • Output Height = 334

The calculator will return the correct width value: 500 pixels.

Calculate Video Ratio

In the above example, we are using an image but the same logic can be applied to a video clip.

For example, we could download a video clip from pixabay.com

The original downloaded video from pixabay.com was 1920 x 1080 pixels (HD Resolution). If we wanted to convert the video into a lower resolution, then we can use the aspect ratio calculator tool above. For example, if I wanted to reduce the width of the video clip to 640 I would enter the following data into the calculator to calculate the correct height.

  • Source Width = 1920
  • Source Height = 1080
  • Output Width = 640

The calculator will return the correct height value: 360 pixels. When adding video content to your website it is important to compress the video content, this will ensure your website page will load faster. Compressing video content will lose image quality but a website page will normally not requires a full HD resolution video clip. In the above example, the original file downloaded from Pixabay was 6.4Mb at 1920 x 1080 pixel resolution. After compression is applied the video clip is reduced to 641kb (less than 1Mb) at 640 x 360 pixel resolution. Note: If you are planning to upload video content to your social media accounts like Facebook or YouTube then it is better to upload full HD resolution and then embed the video into your website pages. At DCP we upload video content to our YouTube channel and then incorporate (embed) video content into our blog posts.

Video Content Aspect Ratios

There are many different types of devices that can be used to display video content. It is important to understand your target devices so when you export video content it will display correctly. It makes sense that device manufacturers work to a set of comment video resolution standards. Listed below are some of the common Aspect Ratios and Video Resolutions.

Aspect RatioResolution
5:41280×1024
4:31024×768, 1600×1200
3:22160×1440, 2560×1700
16:101280×800, 1920×1200
16:9 (HD)1366×768, 1920×1080, 1280×720
17:94096×2160
1.9:1 (4K)3840×2160
32:93840×1080, 5120×1440
1:11920×1920
4:117280×4320

The most common resolutions for TVs, Laptops, Tablets, and computer monitors are:

  • HD Resolution 16:9: 1920×1080, 1280×720
  • 4K Resolution 1.9:1: 3840×2160

When creating video content for social media like Instagram, it is important to understand how a user interacts with the Instagram APP. The Instagram APP is normally viewed in portrait view, so when creating content for Instagram we need to change the dimensions to portrait: 1080 x 1920. As you are aware, there are many different social media platforms that require different video resolutions. To give you a “helping hand” we have listed below links to video documentation for the most common social media platform which allows you to upload video content:

Facebook Video Resolutions

Instagram Video Resolutions

YouTube Video Resolutions

Vimeo Video Resolutions

Twitter Video Resolutions

Pinterest Video Resolutions

Image Content Aspect Ratios Resolutions

Just like videos, images that are uploaded to your website or social media accounts also require a specific aspect ratio and image resolution. For example, YouTube thumbnails are uploaded at 16:9 720p resolution (1280 x 720). Instagram images are uploaded at 1:1 resolution 1080 x 1080. The size of the image uploaded will depend on where the content will be displayed on different social media platforms. To give you a “helping hand” we have listed below links to image documentation for the most common social media platform:

Facebook Image Resolutions

Instagram Image Resolutions

YouTube Thumbnail Image Resolutions

Vimeo Thumbnail Image Resolutions

Twitter Image Resolutions

Pinterest Image Resolutions

Pinterest Image Pin Size Guide

Pin TypeResolutionAspect Ratio
Pinterest Standard Pin1000 x 1500px2:3
Pinterest Square Pin1000 x 1000 px1:1
Pinterest Long Pin1000 x 2100 px1:2.1
Pinterest Infographic Pin1000 x 3000 px1:2.1
Pinterest Carousel Pin1000 x 1500px2:3
Pinterest Collection Pin – Hero1000 x 1500px2:3
Pinterest Collection Pin – Square1000 x 1000 px1:1
Pinterest Story Pin1080 x 1920 px9:16
Pinterest Profile Picture160 x 160 px1:1

FAQs about Image and Video Aspect Ratios

An aspect ratio is the proportional relationship between the width and height of an image or video. It’s usually written as width:height (e.g., 16:9 or 4:3).

Aspect ratios determine how your image or video will appear on different screens or platforms. Using the correct ratio prevents stretching, cropping, or black bars from appearing.

YouTube’s default aspect ratio is 16:9. If your video uses a different ratio, YouTube may add padding (black bars) or crop the content.

  • Feed posts: 1:1 (square), 4:5 (portrait), or 1.91:1 (landscape)

  • Stories and Reels: 9:16 (full-screen vertical)

  • 4:3 is a more square format, common in older TVs and cameras.

  • 16:9 is widescreen, used in modern TVs, monitors, and streaming platforms.

Yes, you can change the aspect ratio using editing software, but it might involve cropping, adding borders, or resizing, which can affect the final quality.

  • Feed: 4:5 (vertical), 1:1 (square), or 16:9 (landscape)

  • Stories: 9:16

  • Cover videos: 16:9

9:16 is a vertical format where the height is greater than the width—commonly used for mobile videos like TikToks, Instagram Reels, and Stories.

1080p typically refers to 1920×1080 resolution, which is 16:9 aspect ratio.

Platforms might add black bars (letterboxing or pillarboxing), crop your video, or scale it incorrectly, affecting its appearance and viewer experience.

Common aspect ratios for print include:

  • 3:2 (standard photo prints like 6×4 or 12×8)

  • 4:3

  • 5:4 (8×10 prints)

Always match your aspect ratio to your desired print size.

Most platforms will adjust or crop media to fit their preferred aspect ratios. It’s best to upload media in recommended formats to avoid unwanted changes.

Yes, especially for web and mobile content. For example, a 1:1 or 16:9 ratio works well for both.

No. Aspect ratio is the shape of the media (e.g., 16:9), while resolution is the size in pixels (e.g., 1920×1080). Different resolutions can have the same aspect ratio.

Popular tools include Adobe Photoshop, Canva, Adobe Premiere Pro, Final Cut Pro, DaVinci Resolve, and online tools like Kapwing and Clideo.

Yes, this tool is completely free to use. 

  • There’s no need to sign up, no software to install, and no hidden fees.
  • It runs entirely in your web browse, no downloads required.
  • You can perform unlimited calculations without any restrictions.

You can use it whenever you need, with no cost or limitations.

Disclaimer: DCP Web Designers are not liable for damage or loss of profits caused by using the Aspect Ratio Tool on this page.