Why does a photo saved as PNG weigh 20 MB, and why does a logo turned into JPG sit on a white box? How each format compresses, what happens to transparency and quality, typical file sizes, and a decision table by use case.
The core of the PNG vs JPG question is how each format compresses. JPG (JPEG) is lossy: it deliberately discards detail your eye is unlikely to miss, which squeezes photographs into very small files. PNG is lossless: every pixel comes back exactly as saved, and it supports transparent backgrounds. The short rule is JPG for photographs, PNG for logos, icons, screenshots and anything with text. Save the same photo as PNG and it typically weighs several times more than the JPG; save a screenshot as JPG and you get grubby smudges around every letter.
To fix a file right now, turn photos that were saved as PNG into compact JPGs with PNG to JPG, or make a lossless working copy before editing with JPG to PNG. When you want a lighter file in the same format, the image compressor is the right tool, and PNG to WebP offers a middle path for the web. If your logo exists as a vector, SVG to PNG produces a crisp PNG at the size you need.
Both formats answer the same question, namely how to store a picture in fewer bytes, with two opposite strategies. Once you see the mechanics, predicting the winner for a given file becomes easy.
Standardised in 1992, JPEG first splits the image into brightness and color components. Because the eye is less sensitive to color detail than to brightness, color is usually stored at reduced resolution. The image is then cut into 8×8 pixel blocks, each block is transformed into frequency components, and fine detail the eye struggles to see is rounded away. The quality slider simply controls how aggressive that rounding is.
On smooth subjects such as sky, skin and foliage, the result is remarkably efficient. Hard edges are the weak spot: black text on a white background picks up a shimmer of “mosquito noise”, and low quality settings reveal visible block patterns.
PNG runs each row of pixels through a prediction filter and then packs the result with DEFLATE, the same algorithm used inside ZIP archives. Nothing is discarded: open the file and you get back exactly what you saved. That works brilliantly on flat color and repeating patterns, and barely at all on the natural grain of a photograph.
The format has several modes: palette mode with up to 256 colors (often called PNG-8), truecolour at 8 bits per channel, and 16 bits per channel. A simple logo in palette mode can shrink to a few kilobytes, while the same logo saved needlessly at 16 bits balloons for no visible gain.
A less discussed JPG trait is generation loss. Open a JPG, make a small tweak and save it as JPG again, and compression runs from scratch, so the damage accumulates. Ten rounds of edit-and-save produce visible degradation, especially around text and edges. PNG has no such build-up, which makes it the right container for work-in-progress files.
To make the difference concrete, take a 12-megapixel phone photo. At 4000 × 3000 pixels and 3 bytes per pixel, the uncompressed image is exactly 36 million bytes, roughly 34 MB. The table shows how typical images of each kind behave in the two formats; your own numbers will shift with content.
| Image | JPG (quality 85–90) | PNG | Winner |
|---|---|---|---|
| 12 MP phone photo | Typically 2–5 MB | Typically 15–25 MB | JPG, by a wide margin |
| Flat-color interface screenshot | Similar size, smudged text | Often equal or smaller, pixel-perfect | PNG |
| Logo with few colors | Halo around edges, no transparency | A few KB in palette mode | PNG |
| Screenshot dominated by a photo | Noticeably smaller | Large | It depends |
The lesson: which format comes out smaller depends on the content, not on whether you call the file a photo or a screenshot. A screenshot that is mostly photograph favours JPG; a photo of an almost flat wall can surprise you as a small PNG.
| Use case | Recommended | Why |
|---|---|---|
| Phone and camera photos | JPG | Small files that open anywhere |
| Interface and error-message screenshots | PNG | Text stays sharp |
| Transparent logos and icons | PNG | Needs an alpha channel |
| Infographics with lots of text | PNG | No smudging around letters |
| Photos sent as email attachments | JPG | Keeps the attachment light |
| Photos on a website | JPG or WebP | Page speed |
| Photo prints | High-quality JPG | Widely accepted by print services |
| Files you will keep editing | PNG | No generation loss |
| Application forms and ID photos | JPG | Forms usually ask for JPG under a KB limit |
A camera or phone already hands you a JPG (or HEIC). Converting it to PNG adds nothing but weight. Archive the highest-quality JPG you have and make smaller copies for sharing. If the photo is going on a website, WebP gives a comparable look in fewer bytes.
The Windows Snipping Tool and the macOS screenshot shortcut both save PNG by default, and that is the right default: menus, code and tables are all hard edges. The exception is a capture that is mostly a photo or a video frame, where JPG or WebP will be far lighter.
The ideal source for a logo is a vector (SVG or PDF); for the web and slides you export a transparent PNG from it. In print, pixels are what count. The common rule of thumb is 300 pixels per inch at the final size, so a 4 × 6 inch print needs about 1200 × 1800 pixels. The DPI value written into the file changes nothing on its own. A high-quality JPG is fine for photo prints, while jobs with fine type and logos are safer as PNG or as the PDF the printer asks for.
Conversion works in both directions, but the outcomes are not symmetrical.
holiday-2024-01.jpg.No. Detail discarded when the JPG was saved is gone for good. Converting to PNG only stops further loss on later saves, and makes the file bigger.
Yes, they are the same format. The three-letter .jpg spelling spread because early Windows versions limited extensions to three characters. There is no need to rename a .jpeg file.
PNG is always a faithful copy of the source, while JPG is close to it depending on the setting. On a photo at around quality 90 you usually cannot see a difference; on a screenshot you notice it immediately. So the honest answer depends on the content.
Platforms generally recompress uploads with their own settings. Upload photos as high-quality JPGs; for text-heavy announcement graphics, a PNG upload often survives that recompression more cleanly.
Further reading: what is WebP for the modern alternative, how to reduce image file size for form and email limits, what is an SVG file for logo sources, and how to choose an image format for all four common formats side by side.
