How to Open a PNG File

What is a PNG file?

PNG (Portable Network Graphics) is a lossless raster image format created in the mid-1990s as a free, patent-unencumbered replacement for GIF. Every pixel is preserved exactly — PNG's DEFLATE-based compression never discards image data the way JPEG's does — which makes it the standard choice for screenshots, logos, icons, line art, and anything with sharp edges or text where JPEG's compression artifacts would be obvious.

Structurally, a PNG file is a sequence of typed chunks, each with its own length, 4-character type code, data, and a CRC-32 checksum covering that chunk. The mandatory IHDR chunk declares the image's dimensions, bit depth, and color type (grayscale, palette-indexed, truecolor, and either of the last two with a full alpha transparency channel added). Optional chunks carry a color profile, physical DPI, a last-modified timestamp, free-form text metadata, and — since a 2017 spec addition — a full EXIF block. That's exactly the chunk structure this page's tool reads directly, verifying each one's own real checksum along the way.

PNG vs JPG: which should you use?

• Use PNG for: screenshots, logos, icons, diagrams, text-heavy images, or anything needing real transparency.
• Use JPG for: photographs and other complex, continuous-tone images, where its lossy compression gives a much smaller file at a visually similar quality.
• PNG files are typically far larger than JPGs for photographic content, since lossless compression can't shrink complex photo detail nearly as much as JPEG's lossy approach can.

Opening a PNG file on any device

1. Windows: double-click it — opens in the Photos app by default.
2. Mac: double-click it (opens in Preview), or press the spacebar in Finder for a Quick Look preview.
3. Linux: opens in whatever the desktop environment's default image viewer is (usually GNOME Image Viewer, Gwenview, or similar).
4. Any browser: drag it directly into a browser window, or use the tool on this page for a preview plus a full metadata breakdown.

Opening a PNG on Android & iPhone

Phones open PNGs natively. Screenshots are often PNGs already (iPhone screenshots always are, and many Android phones save them that way too), so you've probably been opening them for years without noticing.

• iPhone/iPad: a PNG in Mail, Messages or the Files app opens with a tap in Quick Look. To keep a PNG from Safari, touch and hold the image and choose Save to Photos; to keep it as a file instead, use Share > Save to Files.
• Android: PNGs open in Google Photos, the phone's own gallery, or Files by Google. Some Samsung phones let you choose whether screenshots are saved as PNG or JPG in the screenshot settings.
• Attachment won't open? On both platforms, a PNG attachment that shows only a generic icon usually hasn't finished downloading — tap it once and wait, or save it to Files first.

Common PNG file problems and how to fix them

"It appears we don't support this file format" / the image won't display

The file may be corrupted or incompletely downloaded. Use the tool on this page's Chunks tab — if any chunk fails its CRC-32 check, or the file ends abruptly before an IEND chunk, that confirms real corruption rather than a viewer problem.

The image looks fine but has a strange colored background where I expected transparency

Some older software (and certain older browsers) don't render PNG's alpha transparency correctly and instead show a solid color. Check the Overview tab here to confirm the file genuinely has an alpha channel — if it does, the problem is with the viewer, not the file.

The PNG file is much larger than expected

PNG is lossless, so large, detailed or photographic images can produce big files. Check the Overview tab's compression estimate; if it's already highly compressed, converting to JPG (using the button above) is usually the best way to shrink a photographic PNG further.

PNG "transparent" background shows a gray-and-white checkerboard

If you downloaded a "transparent PNG" (often from an image search) and the checkerboard pattern stays visible when you place it on a colored slide or document, the file isn't transparent at all — the checkerboard was painted into the pixels to make it look transparent in search results. Real transparency only looks like a checkerboard in editors; on a slide or web page, the background shows through.

1. Confirm it: drop the file into the tool above. If the Overview tab shows Transparency (alpha): No and a color type without alpha (Truecolor RGB, for example), the checkerboard is fake.
2. Look for the original: on the source site, open the full-size image rather than the preview — some sites serve a flattened preview and the real transparent file only on the download link.
3. Remove the background yourself: Windows 11 Paint has a one-click Remove background button; on a Mac, Preview's Instant Alpha tool (in the Markup toolbar) erases a background color you drag over; on an iPhone or iPad, touch and hold the subject of a photo to lift it off its background, then share or copy it. Each of these produces a PNG with real transparency.

Keep transparency when editing or saving a PNG

A PNG can lose its transparent areas silently when you edit or re-export it. The usual culprits:

• Saving as JPG. JPG has no transparency, so transparent pixels are filled with a solid color — white in most apps, black in some. The PNG to JPG converter on this site fills them with white deliberately; if you need to keep transparency but want a smaller file, use PNG to WEBP instead.
• Older versions of Paint. Classic Windows Paint has no transparency support and fills transparent areas with white when it saves. The current Windows 11 Paint, with layers, can keep transparency when saving as PNG — update it from the Microsoft Store if you don't see a Layers panel.
• Mac Preview's Alpha checkbox. When you use File > Export and choose PNG, Preview shows an Alpha checkbox. Leave it ticked; unticking it flattens the image onto white.

How to make a PNG file smaller

Because PNG never throws detail away, shrinking one means either compressing the same pixels more cleverly or reducing what there is to store. In rough order of how much they save:

1. Reduce the pixel dimensions. A screenshot from a high-resolution display can be 3000+ pixels wide; halving the width cuts the pixel count to a quarter. Use Paint's Resize, Preview's Tools > Adjust Size, or any editor.
2. Reduce the colors (lossy PNG). Tools like pngquant convert a full-color PNG to a 256-color palette PNG with smart dithering. For screenshots, icons and illustrations the result usually looks the same and is often a fraction of the size, transparency included. Web services such as TinyPNG do the same thing, but they upload your file.
3. Optimize losslessly. oxipng or OptiPNG re-run PNG's compression with better settings and strip unneeded chunks without changing a single pixel. Savings are smaller, but it's free quality-wise.
4. Change format for photos. If the PNG is a photograph, it will always be large; JPG or WEBP will typically be many times smaller at no visible cost.

Need the image inside a document instead? The PNG to PDF converter embeds PNGs losslessly, transparency and all.

Related file extensions

Technical references

PNG is formally standardized by the W3C, with the current Third Edition consolidating two decades of errata into one authoritative document.

• Portable Network Graphics (PNG) Specification (Third Edition) — W3C Recommendation — The current official W3C specification defining the PNG file format, its chunk structure, and CRC checksums.

Frequently asked questions