The question of whether JPG or PNG produces smaller files does not have a single answer because the two formats are designed for fundamentally different types of image content. Using the wrong format for a given image type can make a file three to ten times larger than necessary. Understanding when each format excels helps you make the right choice every time without guessing.
What each format actually does
JPEG (Joint Photographic Experts Group) uses lossy compression, meaning it permanently discards some image information during the compression process. The algorithm is designed specifically for photographic content where subtle variations in colour and tone are present across the entire image. It achieves very small file sizes for this type of content by making imperceptible adjustments to pixel values in blocks of 8 by 8 pixels.
PNG (Portable Network Graphics) uses lossless compression, meaning every pixel is stored exactly as it was in the original. The compression reduces file size by identifying and encoding repeating patterns in the image data without losing any information. PNG excels when large areas of the image contain exactly the same colour, such as a solid blue background or a white canvas with black text.
When JPEG produces significantly smaller files
For photographs and any image with continuous colour gradients, JPEG produces dramatically smaller files than PNG. The difference is often ten to one or greater at equivalent visual quality.
A photograph of a person against a natural background might be 500KB as a JPEG at 85 percent quality and 5MB as a PNG. The PNG is ten times larger and looks identical to the human eye. This is because photographs contain continuous variation in every pixel. Every blade of grass, every skin tone, every cloud has subtle colour transitions that JPEG's algorithm handles efficiently but PNG has to store precisely for every pixel.
For web photography, email photos, and any image where the content is photographic, JPEG should be the default choice. Using PNG for photographs is one of the most common ways to unnecessarily inflate image file sizes.
When PNG produces smaller or better files
For screenshots, interface mockups, diagrams, charts, and any image with large areas of solid colour, PNG can produce smaller files than JPEG at equivalent quality because its lossless compression handles uniform colour regions very efficiently.
A screenshot of a text editor with a white background and black text might be 80KB as a PNG and 150KB as a JPEG at 95 percent quality. The JPEG is larger despite being a lower quality format because JPEG's block-based algorithm introduces visible artefacts around the sharp edges of text characters. The PNG looks sharper and is smaller.
For any image where text readability is important, PNG is the right choice. JPEG compression creates ringing artefacts around high-contrast edges, which makes text appear slightly blurry or have a halo effect around it. PNG preserves text edges perfectly.
For images that require transparency (transparent backgrounds, overlaid graphics with soft edges), PNG is the correct format. JPEG does not support transparency at all. An image that requires an alpha channel must be PNG, WebP, or another format that supports it.
The grey zone: images that contain both
Many images contain a mixture of photographic content and graphical elements: a product photo with a text overlay, a social media graphic with a background photo and a headline, a chart with a photographic background.
For these mixed content images, the right format depends on which type of content dominates. If the photographic background covers most of the image area, JPEG with text overlay baked in (at quality 90 or above to reduce text artefacts) is usually the better choice. If the graphic and text elements are the primary content with photography as a supporting element, PNG may preserve quality better.
For mixed content images on the web, WebP is often the most practical solution. WebP handles both photographic and graphical content well, produces files smaller than either JPEG or PNG in most cases, and supports transparency.
Where WebP fits into the comparison
WebP is not a replacement for either JPEG or PNG in the sense that it is a compromise between them. Rather, WebP outperforms JPEG for photographs and matches or beats PNG for graphic content, making it a single format that handles both content types well.
For a photograph, WebP at equivalent visual quality is approximately 25 to 35 percent smaller than JPEG. For a logo or icon with solid colour regions and transparency, WebP is comparable to PNG in file size but adds the option of lossy compression for even smaller files when lossless is not required.
The practical limitation of WebP is compatibility. Modern browsers all support it, but some older automated systems, certain email clients, and some document management tools do not. For images shared outside of a controlled web environment, maintaining JPEG and PNG versions remains important.
Specific comparisons by image type
A 1200 by 800 pixel product photo with natural colour variation: JPEG at 80 percent will be approximately 120KB to 250KB. PNG will be approximately 1MB to 3MB. WebP at equivalent quality will be approximately 80KB to 180KB. JPEG wins clearly over PNG. WebP wins over both.
A 1200 by 630 pixel social media graphic with a solid background, text, and simple shapes: JPEG at 90 percent will be approximately 80KB to 200KB with visible artefacts around text. PNG will be approximately 60KB to 200KB with perfect text edges. WebP lossless will be approximately 50KB to 150KB with perfect quality. PNG and WebP are competitive. JPEG is a poor choice.
A 400 by 400 pixel screenshot of a code editor: JPEG at 95 percent will be approximately 60KB with some text fringing. PNG will be approximately 40KB with perfect text. WebP lossless will be approximately 30KB. PNG wins over JPEG. WebP lossless wins over both.
Making the decision quickly
A simple decision rule covers most situations: if the image came from a camera or contains photographic content without text, use JPEG or WebP. If the image contains text, sharp geometric shapes, or solid colour areas, use PNG or WebP lossless. If the image requires transparency, use PNG or WebP.
When in doubt, try both and compare. Use the Image tools to convert between formats and check both the file size and visual quality before deciding. For web use, also check how the image looks on a high-density screen where JPEG artefacts are more visible.