JPEG, PNG or WebP? Choosing an upload image with Convertix Online

For a photograph, JPEG is usually the practical starting point when the destination accepts it. For a logo or diagram that needs transparency and crisp edges, consider PNG. WebP is another option when the receiving website or application explicitly accepts it. The right choice depends on the destination, the image and the result you inspect—not on a promise that one format always produces the smallest file.

Convertix Online offers JPEG, PNG and WebP output, resizing and a target-size setting for JPEG and WebP. This guide explains how I would choose between those controls. The situation below is fictional: I am preparing a photograph and a logo for a neighborhood workshop listing. No upload, conversion result or acceptance by a real organization is being claimed.

Product information was checked on September 16, 2026. The Web workflow described here is separate from the iPhone interface. The current Convertix App Store listing identifies version 1.2 and also documents image conversion, resizing and target-size reduction.

What does the destination actually require?

Before choosing a format, I would copy the receiving page's requirements into a short note. In my fictional example, the workshop listing accepts JPEG or PNG, requires a landscape image at least 1,600 pixels wide, and sets a 500 KB file limit. Those are invented requirements for this exercise, not universal publishing rules.

I would separate four questions: accepted file types, minimum or maximum pixel dimensions, file-size limit and whether the image needs a transparent background. A file can satisfy three and still fail the fourth. An attractive WebP is useless if this particular form only accepts JPEG and PNG. A tiny JPEG can be under the size limit while being too narrow.

I would also check whether the destination crops the picture. A required aspect ratio is a composition instruction, not another name for resolution. If faces or event details sit near an edge, an automatic crop might remove important content even though the file is technically valid.

That note becomes my decision rule. I would keep it beside the original rather than repeatedly changing settings from memory. If the instructions contradict an error message, I would preserve both and ask the destination to clarify instead of assuming the converter can remove every restriction.

Which format fits which image?

These are editorial starting points, not a ranking of file formats. JPEG is commonly used for photographs; PNG uses lossless compression and can carry transparency. WebP supports both lossy and lossless encoding as a format. The W3C PNG specification and Google's WebP overview document those underlying capabilities.

A format's possibilities are broader than any individual export screen. The current Convertix Online controls provide a JPEG/WebP quality setting; I would not interpret that as a separate, verified lossless-WebP mode. Likewise, a format supporting animation does not mean every converter preserves animation.

For the fictional workshop photograph, I would begin with JPEG because the imagined destination accepts it and the picture does not need transparency. For the separate logo, I would begin with PNG. I would not force both files through the same recipe just because they belong to the same event.

Why are pixels and file size different controls?

Pixel dimensions describe the raster's width and height. File size describes how many bytes the encoded file occupies. They are related, but there is no fixed conversion from one to the other: a detailed photograph and a flat graphic can have identical dimensions and very different encoded sizes.

For an exact arithmetic example, a 4,000 × 3,000 image contains 12,000,000 pixels. Reducing both dimensions by half gives 2,000 × 1,500, or 3,000,000 pixels. The pixel count becomes one quarter of the original. That calculation does not predict that the JPEG will become exactly one quarter as large.

In the fictional listing, a 2,000-pixel-wide result would still exceed the stated 1,600-pixel minimum. I would therefore consider that size before heavily lowering JPEG quality. This is a decision based on the invented requirement, not a claim that 2,000 pixels is optimal for every website.

Convertix Online has a maximum-dimension control. I would inspect its value instead of assuming the imported dimensions will be preserved automatically. After processing, I would read the actual output dimensions again, especially if I also requested a target size. A later size-reduction step may change them further.

What does the target-size setting promise—and what does it not?

In Convertix Online, the optional target-size control applies to JPEG and WebP. The current implementation can adjust encoding quality and then reduce dimensions when needed. If it cannot reach the requested target within its supported processing path, it reports a failure rather than offering a successful result that knowingly exceeds that target.

That makes the control useful, but it does not guarantee a file will satisfy an unrelated form's other rules. A smaller output could fall below a destination's minimum dimensions. A readable photograph could lose a small printed sign. Reaching a byte limit is one condition of success, not the entire inspection.

There is also a unit detail worth checking near a strict boundary. The current Web field labeled KB uses 1,024 bytes per entered unit. A value of 500 therefore represents 512,000 bytes. A destination defining 500 KB as 500,000 bytes has a slightly lower limit. I would leave a margin and inspect the actual file size rather than aim at the boundary without knowing its definition.

For my fictional 500 KB form, I might first try a 450 KB target, then inspect the file and dimensions. That is a proposed starting point, not a measured successful export. The existing storage-units guide explains the broader decimal/binary distinction if those labels need clarification.

Is a quality percentage a universal quality score?

No. A JPEG/WebP quality control is an instruction to the encoder. It is not an objective percentage of the original image's visual quality, nor a guarantee that different formats or browsers produce identical results at the same number.

Browser image encoding can support a quality argument for formats that use lossy compression. The browser API documentation also explains that output-format support depends on the browser. This is why I would compare actual downloaded images rather than treat a slider value as a laboratory measurement.

My visual check would concentrate on the features that matter to the workshop listing: people's faces, lettering on a sign and the edges of equipment. I would inspect the image at its intended display size, then zoom in briefly to understand any artifacts. A magnified imperfection that nobody can see at the destination is different from unreadable text at normal size.

I would compare each candidate with the retained original. Repeatedly using yesterday's compressed copy as today's input makes the comparison harder to understand. Keeping a clean source lets me change one decision at a time and know which result I am evaluating.

What happens to a transparent logo?

Transparency is a separate requirement. A transparent area has information about how the image combines with the background behind it. A white rectangle that looks acceptable on a white page is not the same thing as transparency.

For the fictional workshop logo, I would keep a PNG copy if the destination accepts PNG and the background needs to show through. I would inspect it against both light and dark surroundings. This catches edge halos and unwanted solid backgrounds that may disappear in a white preview.

The current Convertix Online JPEG path fills transparent areas with white. Choosing JPEG therefore changes that part of the result intentionally. I would use it only when a white background is suitable, and I would keep the transparent source for other placements. Converting the white-background JPEG back into PNG will not automatically reconstruct the missing transparent areas.

PNG's lossless encoding also does not mean every transformation is reversible. Cropping removes content; resizing changes the pixel grid. Saving the transformed result as PNG preserves that resulting image without JPEG-style lossy encoding, but it does not restore the discarded source information. That distinction matters when somebody asks for both a lightweight upload and an editable master.

Can every imported format become every exported format?

The input list and output list are different. The current Web tool lists JPEG, PNG, WebP, GIF, BMP and AVIF as image inputs, with decoding subject to the browser's capabilities and the tool's limits. Its output choices are JPEG, PNG and WebP.

GIF is handled as a still image in this workflow. I would not send an animated announcement through it expecting the entire animation to remain. AVIF input also depends on a browser able to decode it. HEIC/HEIF, TIFF, JPEG XL and RAW are not enabled in this Web image workflow as currently published.

If an iPhone photograph arrives as HEIC, changing its filename to end in `.jpg` does not convert its contents. I would obtain a genuinely compatible copy using a workflow that supports the source, then retain the original. I would not keep retrying a format that the current Web converter explicitly excludes.

The iPhone app has its own supported image workflow. Its official listing documents imports from Photos or Files and image conversion, resizing and target-size reduction. That description does not establish that every Web input, control or limit is identical on iPhone, so I would check the interface actually being used.

What should I inspect after downloading?

I would open the downloaded file independently of the converter preview. First I would confirm the format and dimensions. Then I would check that the orientation, crop and background match the intended result. Finally I would read any text and examine the important details at a realistic size.

For the fictional listing, my acceptance note would be simple: destination accepts the chosen format; width remains at least 1,600 pixels; actual file size falls safely below the stated limit; the photograph tells the intended story. I would record the actual result only after seeing it. This article supplies no invented before-and-after file sizes.

I would use filenames that separate the source from the delivery copy, such as `workshop-original` and `workshop-listing`. The name is an organizational aid, not proof of the file's internal format. If the receiving form rejects the copy, I would keep the exact error message and check its stated requirement against the downloaded file.

If the issue is visual rather than technical, another format may not fix it. A poorly framed source, unreadable lettering or an accidental crop can require a better source image or a different composition. Compression cannot recover detail that was never present.

Which version of Convertix would I open for this task?

For this browser-based exercise, I would open Images in Convertix Online, keep the destination's requirements visible and start with a copy of the original. The Web interface identifies its image processing as local to the device; that statement concerns this image workflow, not every unrelated service reachable from the website.

If the files and routine already live on an iPhone, the current Convertix app is another documented option. Product access and commercial conditions should be checked where they are displayed; this guide does not promise unrestricted free processing or identical behavior across platforms.

The useful outcome is a file whose format, dimensions, weight and appearance all fit its purpose. I would preserve the original, keep the accepted delivery copy beside a short requirement note, and stop converting once that job is done. The format is a means to deliver the image correctly, not a competition to win with the smallest possible number.