How to reduce a PNG file size without losing quality

PNG files are great when you need a high-quality image or transparency, but they offer some of the largest file sizes. Large PNG files can slow down your website, hurting the user experience and potentially your SEO efforts.

You can easily reduce the file size using a free online PNG compression tool without sacrificing quality. They apply lossless compression to your images to remove redundant data while keeping the image identical to the original.

In this guide, I’ll break down all the ways to reduce a PNG file size to ensure fast load times on your website.

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Why are PNG files large?

PNG files are usually larger than other image formats, like JPG or WebP, because it uses lossless compression, supports full transparency, and has a high color depth.

With lossless compression, every image detail is preserved to retain the same quality, so the file size isn’t reduced as much as with lossy compression. Lossy compression is used for JPG files, which removes some image data, shrinking the file size even more but also sacrificing some quality.

PNG files also support full transparency, or the alpha channel, which stores extra data for the whole image surface. The alpha channel has to communicate pixel transparency to your device, which contributes to a bigger file size.

As for color depth, PNG images support 24-bit color, or up to 16+ million colors, making it rich in detail. The more color data the image has, the larger the file size becomes.

Best PNG compression tools

The fastest way to reduce PNG images is using an online compression tool. They’re usually designed to reduce the file size only as much as possible to preserve the image quality. Here are the tools I recommend which show no visible quality loss:

• TinyIMG – free online PNG compression tool for bulk optimization
• ImageOptim – free compression application for Mac (has an option for lossy compression)
• PNGGaunlet – Windows application for PNG file compression in batch
• Pngcrush – command-line application for UNIX, LINUX, and MS-DOS

How to reduce a PNG file size

Reducing the file size of a PNG image can be done with multiple tools, but I recommend using any free online image compressor. It reduces the size of your images in bulk and without visible quality loss.

Here’s how to do it with the TinyIMG compressor:

1. Open the TinyIMG PNG compressor on your web browser.
2. Drag and drop the PNG files you want to reduce in size. You can upload up to 10 images at a time for bulk compression. The max size of each file cannot be more than 3MB.
3. The PNG file is available for download once the compression is complete.
4. You can see the difference in the file size of the original and reduced image before you download it.

Other methods to reduce the PNG file size

Aside from reducing PNG files using compression tools or device-specific apps, you can use some other methods. It includes using image editing software like Photoshop or Paint, or using the best image optimization practices. Let’s review all methods in detail.

Paint

If you’re a Windows user, you can change image dimensions using Paint. Reducing the dimensions will also make the file size smaller.

Mac Preview

The only way to reduce the file size without using external tools on Mac is to reduce image dimensions through the Mac Preview app. Once you adjust the dimensions, the file size will also reduce. Keep the lock icon closed while changing dimensions to prevent distorting the aspect ratio.

On Mac Preview, you can also change the resolution to lower the image size, which will reduce the image quality. Avoid overdoing it to prevent visible loss in quality.

Change image dimensions

If you don’t need strict dimensions for your PNG image, then you can reduce the file size by changing them. Proportionally reducing the width and height of an image will give you a much smaller file size.

Crop the image

If you have a PNG image that has unnecessary details near the corners, you can crop it to reduce the file size. For example, if you have a product image with a specific item in the middle on a white background, you can crop a part of the white background.

Change the image format

PNGs use lossless compression, so all of your original image data is intact even after compression, which results in larger file sizes. To reduce the file size, you can convert PNG to JPG or WebP.

JPGs use lossy compression, meaning some redundant image data is deleted when compressed, so image file sizes are smaller without highly visible quality loss.

Meanwhile, the WebP format is developed by Google and is around 25-34% smaller in file size than JPGs and PNGs while at a similar quality.

You can convert images using any online tool, like the TinyIMG PNG to WebP converter or PNG2JPG.

Reduce color depth

PNG images use a high number of colors, which increases the file size. You can try reducing the color depth to make the file lighter, but you’ll need a tool like Adobe Photoshop.

For example, you can save a 32-bit image as a 24-bit or 8-bit image. However, note that this can cause visible quality loss, so preview the image before you save it.

How to compress PNG files without losing quality?

Compressing PNG files can cause quality loss if done incorrectly. Here are the main tips to maintain a high quality even with a lower image size:

• Use lossless compression, which reduces the file size without removing visual data, so the image looks identical to the original version. Lossless compression only removes redundant data and unnecessary metadata.
• Avoid reducing the color depth too much because it can cause visible quality loss, like steps in gradients or shading loss.
• Preview the image before saving to ensure it doesn’t appear blurry, has transparency issues, or loses sharp edges.
• Use WebP as an alternative, which has a 25-34% file size than PNG at a similar quality. It works great for blog or product images on a website and supports transparency, while PNGs are better for logos and icons.

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About the author

Kristina Jaruseviciute

Kristina is a Content Lead at TinyIMG responsible for informing and educating readers on all things Shopify-related. She covers a broad range of topics around SEO, AI visibility, website performance, and conversion rates to help merchants stand out in a competitive landscape.