**Free online image compressor — to 50 kB, 100 kB or 1 MB**

> Free online image compressor: reduce a photo by quality or down to a ceiling such as 50 kB, 100 kB or 2 MB. Every attempt is measured, and nothing is uploaded.

Source: https://appvau.lt/tools/image-compressor/ · updated: 2026-09-11

# Compress a JPEG, PNG or WebP to a quality or to an exact size ceiling

Set a quality and see the measured result, or set a ceiling — 50 kB, 100 kB, 1 MB, anything you type — and let the tool encode repeatedly until the real file fits under it. Every number on the receipt was measured, not predicted.

DROP · PASTE · CHOOSE

Drop an image here

or choose a file. It is opened in this browser tab and never uploaded — this page has no endpoint to upload it to.

## Quality, or a ceiling — they are different problems

Almost every reason to compress an image is one of two, and they want opposite controls. Either you want the picture to look right and the file to be as small as that allows, or something at the other end has a hard limit and the picture has to fit under it. A tool with one slider makes the second case a guessing game.

Aiming for a quality is the right choice for anything you control: images in a page you are building, photographs going into a document, a portfolio. Pick 80 to 85 and stop thinking about it. The reason that band exists is that a JPEG or WebP encoder spends its bits on the parts of an image the eye attends to, and past about 85 the remaining bits go to detail nobody is looking at. Below 60 the block structure the codec works in starts to show along hard edges — the outline of text, a roofline against a bright sky.

Aiming for a ceiling is the right choice when a form says "maximum 2 MB", a mail server will bounce the message, or a visa application will not accept the photograph. There the question is not what looks best; it is what fits.

## How the ceiling is actually reached

A size ceiling cannot be solved analytically. The encoded size of an image at a given quality depends on the content — a photograph of a forest and a photograph of a wall differ by a factor of ten at the same setting — so the only honest way to hit a target is to encode and measure.

This tool walks a published ladder of 17 quality steps, from 95 down to 20, encoding at each one and measuring the result. The first rung that comes in under the ceiling is the answer, and the receipt names it — which means the result is reproducible: the same file at the same quality gives the same bytes, and you can tell somebody else what to do.

If the lowest quality still will not fit, the tool reduces the pixel dimensions by twelve per cent and walks the ladder again, up to nine times. That is what a person would do next, and doing it silently would be the dishonest part — so the receipt says whether the ceiling was reached by quality alone or by quality and resizing. If it cannot be reached at all, that is reported as a failure with the smallest size achieved, rather than handing over a file that misses the target.

The estimate shown while you are choosing is arithmetic over the pixel count and is labelled as an estimate. Every figure in the receipt is a measurement of the file you are about to download.

## What actually fits in an email

The most common ceiling is a mail limit, and the published numbers are misleading in a specific way: they are limits on the encoded message, not on the file. Attachments are base64-encoded, which inflates them by exactly a third, and MIME adds a line break every 76 characters on top of that. So a "25 MB limit" carries about 18.3 MB of actual file, and the gap is where a send failure comes from.

*Mail limits and what they really carry. Read 2026-09-11.*

| Service | Stated limit | Real file budget | What happens over it |
| --- | --- | --- | --- |
| Gmail | 25.0 MB | 18.3 MB | Files over the limit are replaced with a Google Drive link. |
| Outlook.com | 20.0 MB | 14.6 MB | Offers OneDrive sharing instead. |
| iCloud Mail | 20.0 MB | 14.6 MB | Mail Drop carries up to 5 GB for 30 days. |
| Yahoo Mail | 25.0 MB | 18.3 MB | None; the send fails. |
| Proton Mail | 25.0 MB | 18.3 MB | None on the free plan. |
| Exchange Online (work account) | 35.0 MB | 25.6 MB | An administrator can lower or raise it, so check locally. |

The budget column is computed from the stated limit rather than quoted from anywhere, so it can be checked: it is the limit, less five kilobytes for headers and boundaries, divided by the base64 ratio of four thirds and the line-break overhead. For several photographs in one message, one to two megabytes each is comfortable and leaves room for the message itself.

## When compression is the wrong lever

A photograph straight from a phone is around twelve megapixels and four megabytes. Compressing it to a quarter of that is easy and often unnecessary, because the real problem is usually the dimensions: an image displayed in a web page at 800 pixels wide does not benefit from being 4032 pixels wide, and no quality setting fixes that.

Capping the longest edge is therefore the first thing to try, and it is a field on this page for that reason. Halving the dimensions quarters the pixel count, which is a far bigger saving than anything the quality slider will give you, and it costs nothing if the image is never displayed larger. [The resizer](https://appvau.lt/tools/image-resizer/) is the tool when dimensions are the whole job.

Two other cases where compressing is the wrong move. A screenshot or a diagram — flat colour, sharp edges, text — belongs in PNG or lossless WebP; running a JPEG encoder over it produces ringing around every letter and a file that is often larger than the lossless original. And an image that has already been compressed hard cannot be improved by compressing it again: each pass is a fresh loss layered on the last one, and the tool will report a file that is smaller and visibly worse.

## JPEG, WebP or PNG

For a photograph destined for a browser, WebP is the default: at a matched visual quality it is typically 25 to 35 per cent smaller than JPEG, and every current browser reads it. Choose JPEG when the file has to be opened by something else — an older desktop application, a print workflow, a document template, a recipient who will double-click it. Choose PNG only when the content is flat graphics or text, or when transparency has to survive.

PNG has no quality setting at all, which is a frequent source of confusion. It is lossless by definition: there is nothing to trade. "Compressing a PNG" means either accepting its size, reducing its dimensions, or converting it — and [lossless WebP](https://appvau.lt/tools/png-to-webp/) is usually 25 to 30 per cent smaller with identical pixels, which is the free option.

One honest limitation. The encoder here is the one built into your browser, not mozjpeg or cwebp. For the same visual quality a command-line encoder will usually produce a file ten to twenty per cent smaller. What you get instead is a result in under a second, on a file that never left the tab, with no account and no queue — which for one image before it gets sent somewhere is the better trade, and for a library of forty thousand is not.

## Compressing removes the metadata too

The output of this tool is encoded from pixels, so the EXIF block, the GPS coordinates, the XMP packet and any C2PA manifest do not come across. That is usually welcome and occasionally not — a photographer's copyright line goes with it.

If removing the metadata is the actual goal rather than a side effect, [the metadata tool](https://appvau.lt/tools/photo-metadata/) does it without touching the picture at all: it rebuilds the container and copies the compressed image data across byte for byte, so nothing is re-encoded and no quality is lost. Compressing to strip EXIF is paying a real cost for something that is free.

WHAT IT DOES NOT DO

## The limits, stated here rather than discovered later

- Browser encoders are not mozjpeg. For the same visual quality, a command-line encoder will usually produce a file 10-20% smaller; what you get here is instant and private instead.
- PNG has no quality setting. Compressing a PNG means either accepting its lossless size or converting it to WebP or JPEG, which the tool will do.
- A size ceiling that cannot be met by quality alone is met by reducing the dimensions, and the receipt says so. A ceiling that cannot be met at all is reported as a failure rather than quietly missed.
- Re-compressing an image that has already been through a lossy encoder compounds the damage. Start from the original wherever you still have it.

**What is checked:** Every candidate is really encoded and really measured. The size shown is the size of the file you download, not a model of it.

## Questions people ask about this

1. 01 How do I compress an image without losing quality? If "without losing quality" means mathematically identical pixels, convert to lossless WebP or keep PNG — both are typically 20-30% smaller than PNG alone. If it means "without a visible difference", a JPEG or WebP at quality 80-85 is indistinguishable from the original at normal viewing distance and is usually a quarter of the size. The tool shows both sizes so the trade is visible rather than argued about.
2. 02 What size should an image be for email? Gmail and Yahoo cap a message at 25 MB, Outlook.com and iCloud Mail at 20 MB. Those are limits on the encoded message, and base64 inflates an attachment by a third — so a 25 MB ceiling really carries about 18.3 MB of file, and a 20 MB ceiling about 14.6 MB. For several photos in one message, 1-2 MB each is comfortable.
3. 03 Is my image uploaded to compress it? No. The encoder is the one built into your browser, and it runs on the pixels in this tab. The file never leaves the device.
4. 04 Why is my compressed file bigger than the original? Usually because the original was already compressed harder than the quality you asked for, or because a photograph was written as PNG. Re-encoding cannot undo compression that has already happened; it only adds a second pass. The tool reports the change either way rather than hiding an increase.
5. 05 What quality setting should I use? For photographs on a screen, 80-85 is the band where the difference stops being visible and the file stops shrinking usefully. Below 60 the edges around high-contrast detail start to break up. Above 92 the file grows fast for almost nothing. Screenshots and line art are a different problem: they want PNG or lossless WebP, not a quality number.
6. 06 How do I get an image under 100 kB exactly? Choose the size ceiling rather than a quality, and set 100 kB. The tool encodes at each rung of a published quality ladder until the measured file fits, and if quality alone will not get there it reduces the dimensions in 12% steps and says that it did.
7. 07 Should I use WebP or JPEG? WebP for anything shown in a browser: at a matched visual quality it is typically 25-35% smaller than JPEG, and every current browser reads it. JPEG when the file has to be opened by something old, printed, or sent to someone who will double-click it on a desktop.
8. 08 Does compressing remove the location from my photo? Yes, as a side effect: the output is encoded from pixels, so no EXIF, GPS or XMP is carried across. If removing the metadata is the actual goal, the metadata tool on this site does it without re-compressing the picture at all.
9. 09 Why does the estimate differ from the result? Because the estimate is arithmetic over the pixel count and the result is a real encode. The estimate exists so the field is not blank while you are choosing; the page says so, and every number in the receipt is measured.

## Other tools on this site

[All 10 tools](https://appvau.lt/tools/)

- [Image files Image resizer](https://appvau.lt/tools/image-resizer/)
- [Image files PNG to WebP converter](https://appvau.lt/tools/png-to-webp/)
- [Photo privacy Photo metadata viewer and remover](https://appvau.lt/tools/photo-metadata/)

These tools exist because the same problem keeps turning up underneath the app: a photograph says more than the person sending it meant to. App-Vault is the iPhone side of that — an encrypted vault for the files that should not be in the camera roll at all. [What the vault does](https://appvau.lt/photo-vault/), [the cryptography behind it](https://appvau.lt/encryption/) are documented rather than asserted.

[Home](https://appvau.lt/) [Browser tools](https://appvau.lt/tools/) Image compressor

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## Seal the vault.

Free to download. The free tier holds one file. Premium removes the limit — Weekly from $3.99 or Yearly from $29.99 with a 7-day free trial.

[Open App-Vault on iPhone](https://appvau.lt/download/)

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