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How to compress an image on Windows

Windows can resize an image in Photos or Paint, but neither gives you a file-size target. Here is what each one actually does, and when to use something else.

The short answer

Photos app
Resize by dimensions, with a quality slider in recent versions.
Paint
Resize by percentage or pixels. No quality control on save.
PowerToys Image Resizer
Right-click batch resizing. A free Microsoft download, not built in.
Send to → Compressed folder
Makes a ZIP. Saves almost nothing on JPEGs.
Exact KB target
Not available in any built-in Windows tool.
Biggest win
Reduce the dimensions. Everything else is secondary.

Four ways to do it

  1. Step 1: Photos — the best built-in option

    Open the image in Photos, find Resize image in the menu, and choose a preset or enter your own dimensions. Recent versions also show a quality slider and an estimated file size, which makes it the only built-in tool that tells you what you are getting.

  2. Step 2: Paint — quick and predictable

    Open in Paint, click Resize, and enter a percentage or pixel dimensions with the aspect ratio locked. Then Save as → JPEG. Paint gives you no quality control, so the saving comes entirely from the smaller dimensions, but it is fast and always present.

  3. Step 3: PowerToys Image Resizer — for batches

    Install Microsoft PowerToys, then select any number of files in File Explorer, right-click and choose Resize pictures. It handles whole folders at once and remembers your presets. It is free and from Microsoft, but it is a separate download, not part of Windows.

  4. Step 4: A browser tool — when you need an exact size

    No built-in Windows tool can target a specific number of kilobytes. Open the compressor on this page, set a target, and it searches for the highest quality that fits. Nothing is uploaded and there is nothing to install.

Details worth knowing

Why the ZIP trick does not work

Right-clicking and choosing Send to → Compressed (zipped) folder is the most common piece of bad advice about image compression on Windows.

ZIP uses lossless general-purpose compression, and JPEG, PNG and HEIC files are already compressed. There is essentially no redundancy left for DEFLATE to exploit, so a ZIP of a hundred JPEGs is typically one or two per cent smaller than the originals — while being harder for the recipient to open, particularly on a phone.

ZIP is for bundling many files into one. It is not a compression step for images.

What each built-in tool can and cannot do

Photos
Resize with dimensions, and in recent builds a quality slider with an estimated size. The best built-in choice.
Paint
Resize only. Saving as JPEG uses a fixed internal quality you cannot change.
Paint 3D
Being retired; nothing here needs it.
File Explorer
No image compression at all. The ZIP option is not one.
PowerToys
Batch resize with presets and a quality setting. Free, but a separate install.

Nothing in the list targets a file size in kilobytes, which is the one thing upload forms actually ask for.

HEIC files from an iPhone

Windows does not open HEIC out of the box — you will be prompted to install an extension from the Microsoft Store, and the codec is sometimes a paid item.

If you only need the images occasionally, it is usually easier to have them sent as JPEG in the first place, or to convert them. Note that browser-based tools cannot help here either: Chrome and Firefox cannot decode HEIC at all, which is why there is no HEIC tool on this site rather than one that silently fails.

Resize before you compress

The same rule applies on every platform: file size scales with pixel count, so halving the width and height leaves roughly a quarter of the file before any quality setting is touched.

A 4000-pixel photograph going into a document or a web page needs 1600 pixels at most. Do that first, and whatever tool you use afterwards has far less work to do.

One caveat

Menu names and options move between releases. If a step below does not match what you see, the underlying capability is usually still there under a nearby name — and the browser tool on this page works identically on every version.

Do it here instead

These run in your browser on any device, so nothing is uploaded and there is nothing to install.

  • Compress JPEG

    Shrink JPG and JPEG photographs with a quality slider or an exact target size.

    Open the tool

  • Resize image

    By pixels or percentage, aspect ratio locked, across a whole batch.

    Open the tool

  • Bulk compressor

    One setting across a whole folder, processed in parallel, downloaded as a ZIP.

    Open the tool

Questions

Frequently asked questions

Every answer below is present in the page source, expanded, so it can be read without opening anything.

Does Windows have a built-in image compressor?

It has resizing — in Photos and in Paint — which reduces file size substantially. It does not have compression in the sense of targeting a file size, and no built-in tool lets you specify a number of kilobytes.

Does zipping images make them smaller?

Barely. JPEG, PNG and HEIC are already compressed, so ZIP typically saves one or two per cent while making the files more awkward to open. Use ZIP to bundle files together, not to shrink images.

How do I compress an image to a specific size on Windows?

No built-in tool does this. Either install something like PowerToys or IrfanView, or use a browser tool with a target-size mode — the exact-size pages on this site take a number in kilobytes and search for the best quality that fits.

Why can't I open my iPhone photos on Windows?

They are HEIC files, which Windows does not support without an extension from the Microsoft Store. The simplest fix is to ask the sender to switch their camera to Most Compatible, which saves JPEG instead.

Does Paint reduce quality when saving as JPEG?

Yes. Paint re-encodes as JPEG at a fixed internal quality that you cannot adjust. It is fine for a quick job, but you have no control over the trade-off between size and quality.

What is the best free option for a whole folder?

Microsoft PowerToys for local batch resizing, or the bulk compressor on this site, which handles a whole folder in the browser and returns them as a single ZIP. Neither costs anything.

From the blog

Related reading

More background from the blog.

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