Is JPEG different from JPG?

No. They are the same format. The three-letter .jpg extension dates from older Windows systems that limited extensions to three characters.

Does converting PNG to JPG lose quality?

A little, because JPG is lossy, but at the quality levels used for uploads the difference is rarely visible in photos. Transparent areas become white.

Formats

JPG vs PNG vs WebP: Which Format to Use for Uploads

By FitKB · Updated November 11, 2026 · 2 min read

Quick answer

Use JPG for photos you upload to forms: it is accepted almost everywhere and gives small files. PNG is lossless and best for screenshots and graphics, but photos saved as PNG are several times larger. WebP is smaller than JPG at the same quality, but many forms still refuse it.

Open the Compress Image to 100KB tool

The short comparison

JPG, PNG and WebP compared for uploading photos
Format	Compression	Transparency	Best for	Accepted by forms
JPG / JPEG	Lossy	No	Photos	Almost always
PNG	Lossless	Yes	Screenshots, logos, text	Often
WebP	Lossy or lossless	Yes	Photos and graphics on the web	Sometimes
HEIC	Lossy	Yes	Storage on Apple devices	Rarely

JPG: the safe default for photos

JPG (also written JPEG; the two extensions are the same format) has been the standard for photos since the 1990s. It discards fine detail that is hard to see, controlled by a quality setting. Every browser, phone and upload form understands it, which is why FitKB saves JPG by default.

PNG: perfect copies, large files

PNG keeps every pixel exactly, which is ideal for screenshots, diagrams and text. Photos have so much fine variation that lossless compression barely helps, so a photo saved as PNG is often three to ten times larger than a good JPG. Converting a PNG photo to JPG is usually the quickest way to meet a size limit.

WebP: smaller, but check the form

WebP was developed by Google for the web. At similar visual quality it is typically smaller than JPG, and all major browsers can display it. Many government and exam portals still accept only JPG, so choose WebP only when the form explicitly lists it. FitKB offers WebP in the Format setting.

Which should you choose?

A form that says JPG or JPEG: JPG.
A form that lists several formats and has a tight KB limit: WebP if listed, otherwise JPG.
A screenshot of text or a document: PNG if accepted, otherwise JPG at a high quality.
An iPhone HEIC photo: convert to JPG first, as explained in how to upload HEIC photos.

How JPEG compression works, briefly

JPEG splits the image into small blocks of 8 × 8 pixels and describes each block as a mix of smooth patterns. Fine detail that the eye barely notices is stored less precisely or dropped. The quality setting decides how much is dropped. Colour detail is usually stored at lower resolution than brightness, because our eyes are less sensitive to it.

That is why JPEG is excellent for photos, where small losses are invisible, and weaker for sharp text and line art, where the losses show up as faint smudges around edges.

What quality numbers mean

Approximate effect of JPEG quality on a typical photo
Quality	Typical look	Typical use
90 to 95	Indistinguishable from the original	Archiving, printing
75 to 90	Very good; differences only when zoomed in	Websites, email, most uploads
50 to 75	Good; slight softness in fine textures	Strict upload limits
Below 50	Visible blocks and smudging	Only when the limit leaves no choice

Quality numbers are not standardised between programs, so quality 80 in one app is not exactly the same as quality 80 in another. FitKB shows the quality it chose under the preview.

Questions people also ask

Is JPEG different from JPG?: No. They are the same format. The three-letter .jpg extension dates from older Windows systems that limited extensions to three characters.
Does converting PNG to JPG lose quality?: A little, because JPG is lossy, but at the quality levels used for uploads the difference is rarely visible in photos. Transparent areas become white.