Helga Written by Helga

How To Fix Email Signature Images Changing Size?

Getting images to display correctly in your email signature can be a hassle. Even if everything looks good in your editor, sometimes the images will become much larger in your email client, distorting the design and making the signature virtually unusable.

But what can you do if your Gmail or Microsoft Outlook signature image is too big? And what are the best ways to manage Gmail and Outlook signature size changes?

Let’s look at the main causes of an enlarged image and ways to fix it below, helping you find the best format for email signature images to ensure they display correctly.

Understanding the cause: DPI and image dimensions

There are a few reasons why an image in an Outlook or other email client signature is too big. To understand them, we must look at the role DPI plays in the image size, as well as how image dimensions can impact the formatting.

DPI and its role in image sizes

DPI, or Dots per Inch, is a way to measure the size of the image in terms of pixels. Digital photos are like mosaics in that they contain a certain number of pixels (or dots) that make up the entirety of the picture.

Email clients use DPI counts to evaluate how big the image should be together with the image dimensions. When you have a DPI count that’s significantly higher, email clients like Microsoft Outlook and Apple Mail may scale the images using that value, causing them to display much larger than you intended.

Missing or incorrect dimensions

Email clients recognize how to display an image based on its dimensions (width and height in pixels). For example, when you add a logo to your email signature, the email client will look at the pixel dimensions that define its width and height, providing information on how it should look.

That’s why a common reason why a logo in an email signature is too big has to do with email signature image size featuring incorrect or unrecognized dimensions.

Sometimes, email clients might even ignore set dimensions altogether, instead displaying the image in its native size, even if you set other dimensions.

Fixing the image

Most of the best email signature examples feature images. So, you need to figure out how to solve the issue of an Outlook signature image size changing in a way that’s aligned with how your signature should look. Additionally, consider how different email clients like Gmail and Apple Mail may alter your signature's look.

The solutions below will help you learn how to create an email signature with quality pictures that display correctly on your email client.

Checking the image DPI

The first thing you should check is whether your image DPI isn’t too high. To do that, find the image and follow this process on your Windows or Mac device:

  • On Windows, right-click on the image, select Properties -> Details tab, and then look for the Horizontal DPI and Vertical DPI values.
  • On Mac, right-click on the image, choose Get Info -> General, and find the image dimensions.

How to change the DPI of your images

If you want to change the DPI value of an image, the most popular tool for the job is Photoshop. Here’s a step-by-step process:

1. Open your image in Photoshop.

2. Click on Image -> Image Size.


3. In the Resolution field, enter the new DPI value you want to use (96 DPI for Outlook and 72 DPI for Gmail and Apple Mail).


4. Save your image.

If you don’t want to use a paid image processing software like Photoshop, there are free alternatives like GIMP:

1. In GIMP, go to File -> Open and select your image.


2. Go to Image -> Print Size.


3. In the Print Resolution dialog box, adjust the X and Y resolution. Make sure that the dropdown is in pixels/inch.


4. Save your image.

Image DPI recommendations for email signatures

There are no hard rules for how many DPIs you should use on different email clients. That being said, there are best practices you can follow:

  • For Gmail and Apple Mail, stick to 72 DPI.
  • For Microsoft Outlook, the image file should be 96 DPI.

Setting image dimensions

If you’re dealing with a Gmail signature not showing up because of incorrect dimensions, you’ll need an image processing tool to adjust them, just like when adjusting the DPI.

If you’re using Photoshop, follow this process:

1. Go to File -> Open and select your image.

2. Head to Image -> Image Size.

3. In the Image Size dialog box, adjust the Width and Height in pixels.


4. Click Save.


1. Go to File -> Open and select your image.

2. Head to Image -> Scale Image.


3. In the dialog box, adjust the Width and Height. If needed, choose pixels in the dropdown box.


4. Click Save.

Additional tips

To avoid hassles with custom dimensions in PNG images, you should follow the guidance on picture specifications for the email client you’re using. But there are also a few additional tips that can make it easier to ensure your email signature looks great.

Use a pre-sized image for the signature

The best way to avoid potential issues with image resizing, consider using images that are already pre-sized to work well for your email signature. Images with the right native dimensions and DPI will have a much lower chance of displaying incorrectly.

To pre-size your images, you can use image editing tools like Canva or PicMonkey, which allow creating images with specific dimensions.

Test the signature

Even if you follow the best practices of email signature design and resize the images in advance, there’s always a chance you might miss something.

So, once you save your signature, it’s a good idea to test it by sending a few emails to yourself or a colleague. You should also test the signature across different email clients, including Gmail, Outlook, and Apple Mail, as well as mobile clients like the built-in Mail apps on iPhones and Android devices, and dedicated mobile apps for Gmail, Outlook, Yahoo Mail, etc. That’s the best way to ensure wider compatibility and avoid formatting issues.


If everything displays correctly, you can then confidently use the email signature in all of your email communications.

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CMO at Newoldstamp at Newoldstamp

Helga is a growth marketer with 7+ years of experience. Since 2015 Helga has switched to SaaS market. Prior to joining NEWODLSTAMP she successfully cooperated with several SaaS companies that provide top-notch solutions for marketers.

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