JPG · file weight only
Increase image
size for JPGs.
Raise a JPG to an exact KB floor without touching its width, height or format. The encoder is pushed to the quality ceiling your pixels allow, and the remainder is topped up with a comment segment every viewer ignores.
No upload · no sign-up · no watermark
01 · The ceiling
Why a JPG has a ceiling — quality 100 is not “more detail”
JPEG is a lossy format. Every save runs the image through a discrete cosine transform, divides the result by a quantisation table, and discards what that table marks as invisible. Setting quality to 100 only shrinks the divisors to their minimum; it does not switch the transform off. The file grows to the largest that pixel grid can support, and then it stops.
That stopping point is what separates a JPG from a PNG here. A PNG absorbs weight indefinitely because its text chunks are unbounded. A JPG hits a hard ceiling at maximum quality, and everything beyond it has to ride in comment segments — real bytes, but not picture bytes.
Chroma subsampling moves the byte count more than quality does
Most encoders, including the one inside your browser, store colour at half resolution in both directions — 4:2:0 — because the eye resolves brightness far better than hue. That single decision removes roughly half the colour data before quality is even considered. The same image at 4:4:4 is commonly 30–50% heavier at an identical quality number, which is often the difference between missing a size floor and clearing it.
Progressive encoding makes the same picture smaller
A progressive JPEG stores the image in several passes, and that compresses slightly better than the single-pass baseline layout — typically 5–8%. Useful when a portal sets a ceiling; mildly unhelpful when it sets a floor, since the ceiling of achievable weight drops with it. The picture is identical either way. Only the byte count moves.
What the encoder restores, and what it cannot
Re-encoding at maximum quality recovers detail a previous save discarded only where the surviving pixels still describe it. It cannot invent texture that was already smoothed away, and it cannot raise resolution. Anything the earlier save destroyed is gone for good — the tool's job is to stop losing more.
02 · The mistakes
Increase image size JPG: three things people get wrong
Saving the JPG as a PNG and renaming it back
This makes the file bigger on disk and useless to the form. A PNG wrapped in a .jpg name fails MIME sniffing on any portal that inspects the real type, and the extension never changed what the bytes are. This tool keeps the format it was given and never renames.
Scaling the picture up to add weight
It works, and it is the wrong fix. The file gets heavier because there are more pixels, then the form rejects it for exceeding the maximum width and height — a different error, from the same form, one upload later. File weight and pixel dimensions are separate dials, and only one of them is being turned here.
Assuming the extra bytes are extra quality
Past the encoder's ceiling the additional weight is a comment segment every viewer ignores. That is enough to pass a size check and not enough to survive a portal that re-encodes uploads. The result panel states how much of the output is metadata, so the distinction is never hidden.
03 · The mechanism
How the size is reached
Re-encode at the highest quality those dimensions can hold
The encoder is pushed until the file is as large as your existing pixels allow. These are real image bytes, and they survive a portal that re-encodes whatever it receives.
Top up the remainder with declared metadata
If maximum quality still lands under the target, the gap is filled with a standards-compliant segment — a JPEG comment, a PNG tEXt chunk, a WebP JUNK chunk. Every viewer ignores it; pixel data, dimensions and DPI stay untouched.
Portals that re-encode every upload will strip metadata, and the file falls back to its real-pixel weight. That is why the quality step runs first — bytes carried by pixels survive re-processing; bytes carried by metadata do not.
What stays the same
04 · Questions
Questions people actually ask
How do I increase a JPG file size without changing its dimensions?
Drop the JPG in, set the target, and press the button. The encoder runs at the highest quality your existing pixel grid can hold, and any remaining gap is filled with a standards-compliant JPEG comment segment. The width and height are read before and after, and they never differ.
Why does my JPG stop growing before it reaches the target?
Because maximum quality is the ceiling for that pixel grid — a 640×640 photo cannot legitimately weigh 1 MB. Past that point the tool chains comment segments to reach the number. Those bytes satisfy a file-size validator; they do not add picture data, and a portal that re-encodes uploads will strip them.
Does increasing a JPG's file size improve its quality?
Only up to the encoder's ceiling. Below it, extra weight means less aggressive compression and genuinely more recoverable detail. Above it, extra weight is metadata. The result panel reports which side of that line the output landed on.