Frustrated with Your Website Images? A Step-by-Step Sizing Guide for WordPress Websites

If you’ve ever managed a WordPress website, you know the feeling. You have a photo you want to use, but getting it to look sharp and load quickly feels like a dark art. It stretches, it blurs, or it slows the whole page down. It’s a common frustration, but the sizing part of the puzzle is something you can solve.

This is your step-by-step professional guide to finding what size your images should be for your WordPress site.

The Short Version (TL;DR)

• Start with Quality: Always begin with a large, high-quality source image. You can make an image smaller, but you can never make a small one larger without it becoming blurry.
• For Perfect Accuracy: Use your browser’s “Inspect” tool to measure the image container on your page, then prepare your master file at double that width (the ‘2x Rule’).
• A Quick-Start Guide: In a hurry? As a rough starting point, these sizes work for many modern themes:
  • Full-Width Banner: 2560px wide
  • Main Blog/Content Image: 1600px wide
  • Small Image (Headshot/Icon): 400px to 600px wide
• Choose the Right Format: Use WebP for photos. If not, use JPEG. Only use PNG for graphics that need a transparent background.
• Always Compress: No matter the size, run your final image through a tool like TinyPNG.com before you upload it to reduce its file size.

Why Getting Images Right Matters for Your Business

Getting your images right directly impacts your business by improving your site’s speed. A faster site means fewer visitors leaving, a better ranking on Google, and a more professional brand image. When a website feels slow, large and unoptimised images are one of the most common culprits. This performance drop might not be obvious on your office’s fast internet connection, but it’s critical for a potential customer on their phone with a weak signal.

The Expert Method for Sizing Your Images

This guide will give you a reliable process for finding the correct dimensions for the vast majority of images on your site.

Step 1: Start with a High-Quality Source Image

This is the golden rule. All the resizing techniques in the world won’t save a low-quality image. You can always make a large, high-resolution image smaller, but you can never make a small image larger without it becoming blurry and unprofessional. If your source photo is already smaller than the final size you need, you must find a higher-quality version.

Step 2: Understand the ‘One Master Image’ Principle

On a modern, well-maintained WordPress site, you only need to upload one single, high-quality, well-prepared master image. Your website will automatically create and deliver smaller, appropriate versions to visitors on different devices.

Step 3: Find the Container Size with Browser Inspector

This is the most accurate way to find the exact size an image is displayed at on your site.

1. Open your website in a desktop browser like Chrome or Firefox.
2. Right-click on the image you want to replace, or the space where an image goes, and select “Inspect” from the menu.
3. A code panel will open. In the top-left of this panel, click the element selector icon (it looks like a square with a pointer).
4. Hover directly over the image or its container. A tooltip will appear showing the dimensions, for example 800 x 450. The first number is the width. Make a note of it (e.g., 800px).

Step 4: Apply the ‘2x Rule’ for Perfect Sharpness

To ensure your images look crisp on high-resolution screens, your master image should be twice the width you just measured. This is why starting with a large, high-quality source image (Step 1) is so important.

• If your image container is 800px wide, prepare your master image at 1600px wide.
• If a headshot container is 150px wide, prepare it at 300px wide.

Step 5: Choose the Right File Format

Before you save your resized image, choosing the correct format is essential for balancing quality and file size.

• WebP (Best Choice): This is the modern standard for the web. It provides excellent quality for a much smaller file size and is supported by all current browsers. Use it for photos whenever possible.
• JPEG (Good Alternative): If you can’t save as WebP, JPEG is the best choice for all photographic images.
• PNG (For Graphics Only): Use PNG only for logos, icons, illustrations, or any graphic that requires a transparent background. Do not save photos as PNGs; the file size will be unnecessarily large.

How to Easily Convert to WebP

You don’t need special software to create a WebP file. The easiest method is to use an all-in-one online tool. Services like TinyPNG.com or Squoosh.app will often automatically convert your uploaded JPEG or PNG to WebP if it provides the best result.

Step 6: Compress Your Final Image

This is the final, crucial step. After resizing and saving in the correct format, you must compress your image. Use a free online tool like TinyPNG.com before you upload the file to WordPress.

Important: When This Guide Isn’t Enough

This step-by-step process will work for most standard images. However, you might still be frustrated by two common issues where sizing alone is not the solution.

1. Complex Components like Sliders: This method may not work reliably for interactive image sliders, where image behaviour is controlled by complex code.
2. Awkward Cropping and Stretching: If an image’s key feature gets cropped out on mobile, that is an issue of responsive design controlled by your website’s theme, not just the image’s initial size.

Solving these more advanced challenges is not as straightforward as finding the right dimensions.

At FlyingFish.ie, we handle these complexities for our clients every day. When we build a site, we often provide a simple ‘cheat sheet’ with the exact image sizes needed, removing the guesswork.

For clients on our Website Care Plans who want the best possible performance, we offer an advanced image optimisation add-on. This goes beyond manual preparation. Our premium software can be configured to run on the server after you upload, automatically handling three key tasks:

1. Converting images to the fast, modern WebP format.
2. Optimising not just your master file, but every single one of the smaller versions WordPress creates.
3. Implementing advanced browser and server caching, telling a visitor’s browser to ‘remember’ your pictures so they load instantly on repeat visits.

This automated, server-level approach achieves a level of performance that manual preparation alone cannot match.

If you’re struggling with images that go beyond simple sizing, or want this entire process handled for you, get in touch for a professional consultation.