Is JPEG or PNG Smaller?

The short answer: JPEG is almost always smaller for photographs and complex images, often by a factor of 5x to 10x. However, PNG can actually produce smaller files for simple graphics with few colors, solid backgrounds, and sharp geometric shapes. The reason comes down to how each format compresses data. JPEG uses lossy compression that discards information the human eye is less sensitive to, achieving dramatic size reductions. PNG uses lossless compression that preserves every pixel, which works brilliantly for simple patterns but struggles with the random variation found in photographs. Understanding when each format wins on file size helps you make the right choice every time and avoid wasting bandwidth or storage space.

Why JPEG Is Usually Smaller

JPEG compression works by analyzing the image in 8x8 pixel blocks and applying the Discrete Cosine Transform (DCT) to convert pixel data into frequency components. It then discards high-frequency data that represents fine detail the human eye is least sensitive to. This is extremely effective for photographs because photos contain enormous amounts of high-frequency information: subtle color gradients, noise, texture variations, and fine details that consume large amounts of data but contribute minimally to perceived quality. By selectively removing this data, JPEG can represent a photograph in a fraction of the space that lossless formats require. A typical 12-megapixel photograph that would be 15 to 25 MB as a PNG file compresses to just 1 to 4 MB as a quality-90 JPEG, an 80 to 95 percent reduction in file size.

When PNG Is Actually Smaller Than JPEG

PNG uses DEFLATE compression (similar to ZIP), which looks for repeating patterns in the data. When an image contains large areas of identical color, like a simple logo on a white background or a diagram with a few flat colors, PNG can encode those repeating patterns incredibly efficiently. JPEG, on the other hand, processes every 8x8 block independently regardless of how simple the content is. For a solid-color area, JPEG still applies its full DCT and quantization pipeline, and the block boundaries themselves add overhead. This means JPEG can actually produce larger files than PNG for very simple images.

Real-World File Size Comparisons

To illustrate the difference concretely, here are typical file sizes for the same image saved in both formats. These numbers are based on standard settings: JPEG at quality 85 and PNG with default compression. Actual results vary depending on image content and resolution, but the ratios are consistent.

The Science Behind the Size Difference

The core reason for the size difference lies in what each compression algorithm optimizes for. PNG's DEFLATE algorithm excels at finding and encoding repeated patterns. A row of 1000 identical blue pixels compresses to essentially nothing because the algorithm says "repeat blue 1000 times." But in a photograph, no two adjacent pixels are exactly the same. Every pixel has slightly different RGB values due to natural color variation, sensor noise, and lighting gradients. PNG must encode each unique value individually, producing enormous files. JPEG's DCT-based approach works in the frequency domain. Instead of encoding individual pixel values, it encodes how quickly colors change across each 8x8 block. Smooth gradients and subtle variations compress to near-zero because they have low frequency components. Only sharp edges and fine details require significant data. Since photographs are predominantly smooth gradients and subtle variations, JPEG compression is extraordinarily efficient for photographic content.

The WebP Alternative: Smaller Than Both

If your primary goal is minimizing file size, there is a third option that beats both JPEG and PNG in most scenarios. WebP, developed by Google, uses more advanced compression algorithms derived from the VP8 video codec. Lossy WebP produces files 25 to 35 percent smaller than equivalent-quality JPEG. Lossless WebP produces files about 26 percent smaller than PNG. WebP also supports both transparency and animation, making it a single format that can replace JPEG, PNG, and GIF for most web use cases. With over 97 percent global browser support, there is very little reason not to adopt WebP for web delivery in 2026.

Practical Recommendations

Choosing the right format for file size does not have to be complicated. Follow these simple rules and you will get the smallest files in every scenario.

Frequently Asked Questions