JPG vs PNG vs WebP for Form Uploads and Websites (Measured)
Published September 17, 2026 · By the TryDocsy team
Format advice usually stops at “JPG for photos, PNG for graphics”. That is a fair start, but it doesn't tell you how big the difference is, or what to do when a portal accepts only one format. We ran three typical images through all three formats and recorded the size of every result.
Short answer
For government and exam portals, use the format the notice names, which is almost always JPG or JPEG for photos and signatures. For your own website, WebP gave the smallest files in every test: 62,982 bytes for a photo that was 118,758 bytes as a JPG at the same quality setting. Use PNG only for images that need transparency or pixel-exact edges, and never convert a JPG photo to PNG hoping to improve it.
The three formats in one paragraph each
JPG (also written JPEG) throws away detail the eye is unlikely to notice, and a quality setting controls how much. It has no transparency. Every camera, phone, printer and upload form understands it, which is why portals default to it.
PNG keeps every pixel exactly, and supports transparency. That makes it right for logos, icons, diagrams and anything you will edit again, but it is a poor container for photographs, because the natural noise in a photo is expensive to store without loss.
WebP was designed for the web and can work either way, lossy like JPG or lossless like PNG, with transparency in both modes. Can I use reported 96.82% global browser support when we checked on 17 September 2026. Outside browsers the picture is patchier: some older desktop software and most form portals still won't take a .webp file.
What we measured
We used three images that represent what people actually convert: a 1920 × 1200 landscape photo (a 518,265-byte JPEG), a 1280 × 800 screenshot of a web page with text and icons (a 180,089-byte PNG), and a 512 × 512 logo with a transparent background (a 5,675-byte PNG). Each went through the Universal Image Converter to every output format. The quality slider only applies to JPG and WebP, so PNG has one row per image.
| Image (original size) | JPG q90 | JPG q75 | WebP q90 | WebP q75 | PNG |
|---|---|---|---|---|---|
| Photo, 1920 × 1200 (518,265) | 197,144 | 118,758 | 116,236 | 62,982 | 1,865,346 |
| Screenshot, 1280 × 800 (180,089) | 109,651 | 74,649 | 55,744 | 39,208 | 324,225 |
| Transparent logo, 512 × 512 (5,675) | 16,031 | not tested | 6,134 | not tested | 12,325 |
Five things the numbers show
- WebP was the smallest every time. At the same slider value it came in at 53 to 59 percent of the JPG size for the photo and about half for the screenshot.
- Saving a photo as PNG makes it huge without making it better. The photo grew from 518 KB to 1.87 MB, about 3.6 times the original, and it can't regain detail the original JPEG already discarded.
- Re-saving a PNG in the browser made it bigger. The screenshot went from 180,089 to 324,225 bytes and the logo from 5,675 to 12,325, because the original files came from encoders that compress PNG harder than a browser canvas does. If you already have a PNG, keep it rather than converting PNG to PNG.
- JPG can't hold transparency. The logo's transparent corners came out solid white in the JPG, and the file was nearly three times the size of the original PNG. WebP kept the transparency.
- A screenshot doesn't have to be PNG. Converted to JPG at quality 90 it shrank to 109,651 bytes, and when we zoomed in on its body text we could not see a difference from the PNG. Below that quality, look closely at small text before you use it.
For exam forms and government portals
Here the decision is made for you. Portals validate the file type and often the extension too, and a WebP renamed to .jpg is still a WebP inside. The UPSC One Time Registration FAQ, for instance, says photographs and signatures must be scanned in JPG/JPEG format, and the photo ID must be a PDF only. Read the notice for your exam and match it exactly.
- Photo or signature asked for as JPG: if your phone saved a PNG, HEIC or WebP, convert it with PNG to JPG or the universal converter, then check the size limit.
- Size limit in KB: convert first, then use Compress Image to reach the number. Converting last can undo the compression.
- Signature on white paper: JPG is fine, because there is no transparency to lose. A signature on a transparent background turns white when saved as JPG, which is what most forms want anyway.
- A WebP downloaded from a website: portals rarely accept it. WebP to JPG fixes that before you upload.
For your own website or online shop
Page weight is what matters here, so WebP is the default choice for photos and screenshots. Swapping our photo from a quality 90 JPG to a quality 75 WebP would cut it from 197 KB to 63 KB. Across a product page with twenty images, that difference adds up to seconds of loading on a slow mobile connection.
- Photos and banners: WebP at quality 75 to 85. Keep a JPG copy if you also send the images by email or to marketplaces that want JPG.
- Logos and icons: SVG if you have the vector file, otherwise lossless PNG or WebP with transparency.
- Screenshots in blog posts: WebP. Only fall back to PNG for images with fine one-pixel lines, such as diagrams, where lossy formats blur edges.
- Resize before converting. A 4000-pixel-wide photo in an 800-pixel column wastes more bytes than any format choice saves.
Quick decision table
| Situation | Use | Why |
|---|---|---|
| Exam or job portal photo and signature | JPG/JPEG, unless the notice says otherwise | Portals validate type; JPG is what they ask for |
| Photo on your website | WebP | Smallest file in our tests at equal slider settings |
| Logo with a transparent background | PNG or WebP | JPG turned the background white |
| Screenshot for a document or email | JPG at quality 90 or higher | Much smaller than PNG, text still sharp |
| Image you will edit again | PNG | Lossless, so repeated saves don't degrade it |
| Printing at a shop | JPG at high quality | Universally accepted by print kiosks |
How we measured
- Samples: photo.jpg is the 1920 × 1200 img19 wallpaper that ships with Windows 11 (518,265 bytes); screenshot.png is a 1280 × 800 capture of the trydocsy.com PDF tools page (180,089 bytes); logo.png is a 512 × 512 blue circle with white text on a transparent background, drawn with Pillow (5,675 bytes).
- Tool: /convert/universal-image-converter from the development build of 17 September 2026 in Microsoft Edge, quality slider set to 90 or 75 for JPG and WebP. Byte counts are the downloaded files; format and transparency were confirmed by opening each output with Pillow.
- Browser support figure: caniuse.com WebP page, global usage, read the same day.
Frequently asked questions
Does converting a JPG to PNG improve its quality?
No. PNG stores exactly what it is given, so it preserves the JPG's existing compression artefacts, just in a much bigger file. Our photo grew from 518 KB as a JPG to 1.87 MB as a PNG with no visible change.
Can I rename a .webp file to .jpg to upload it?
It may pass a check that only looks at the extension, but many portals inspect the file contents, and some image viewers will refuse to open it. Convert it properly so the file really is a JPEG.
What quality setting should I use for JPG?
Quality 90 is a safe default for documents and anything with text. For photos on the web, 75 made our photo about 40 percent smaller than 90 did. If a portal gives a KB limit, let a target-size compressor pick the quality for you.
Why is my converted PNG larger than the original PNG?
Browsers use a fast PNG encoder that doesn't squeeze files as hard as desktop tools or the apps that made your original. The pixels are identical, but the file is bigger. Keep the original PNG unless you need a different format.
Is AVIF better than WebP?
AVIF can be smaller still, but browsers can't reliably encode it from a canvas, so this converter does not offer AVIF output. For a web page today, WebP is the practical choice.
Tools used in this guide
Sources
- Can I use: WebP image format (read September 17, 2026)
- MDN: HTMLCanvasElement.toBlob() (read September 17, 2026)
- UPSC One Time Registration: frequently asked questions (read September 17, 2026)
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