What you will learn
- Tell the difference between a photo's size in pixels and its file size in KB or MB.
- Pick the right format (JPEG, WebP or PNG) and the right setting for each use.
- Shrink up to 30 photos at once and save them to your computer or phone.
- Protect your privacy by removing the GPS location hidden in your photos.
Module 1
Understanding photo file size
Pixels and file size: two different measures
A digital photo is a mosaic of tiny coloured dots called pixels. A recent phone takes photos of about 4000 × 3000 pixels, which is 12 million dots, and sometimes far more (up to 48 million).
The file size, often called its “weight”, is how much storage the file takes up. It is measured in kilobytes (KB) and megabytes (MB): 1 MB equals 1000 KB. A phone photo usually weighs 3 to 5 MB.
The two are linked but not the same thing: more pixels means a heavier file, but the way those pixels are stored matters just as much as how many there are. Yet a typical computer screen only shows about 2 million pixels (1920 × 1080). So to look at a photo on screen, 12 million pixels is far more than you need.
Why your photos are so heavy
Phone makers want photos you can zoom into, crop or print in a large format. So they record as much detail as possible, including subtle shades the eye never notices on a screen.
The result: ten holiday photos quickly add up to 40 MB. That is too much for most e-mail services, which refuse attachments over 20 to 25 MB. It is too much for a website as well: a page full of heavy photos takes several seconds to appear on a phone using 4G, and Google notices. And many online forms (official paperwork, job applications, insurance claims) reject any file over 1 or 2 MB.
The good news: for on-screen use, you can divide that weight by 10 with no visible difference.
Resizing and compressing: what the tool does
There are two ways to make a photo lighter.
- Resizing: reducing the number of pixels. Taking the long side from 4000 down to 2000 pixels divides the number of pixels by 4, and the file size roughly follows.
- Compressing: storing the pixels more cleverly. Lossy compression (JPEG, WebP) removes the least visible details, such as very slight variations in a blue sky. Lossless compression (PNG) keeps every pixel exactly as it was, but saves much less space.
The quality setting (from 40 to 95 in the tool) controls how much lossy compression is applied. Between 75 and 85, the difference is invisible on screen. Below 60, small blurry squares or smudges may appear around edges.
Be careful: lossy compression cannot be undone. Always keep the original, especially if you want to print the photo.
JPEG, WebP, PNG: which format should you choose?
- JPEG (.jpg files): the universal photo format, readable everywhere for over thirty years. The best choice for an e-mail, social networks or an online form.
- WebP: a newer format created by Google, 25 to 35% lighter than JPEG at the same quality. All recent browsers and WordPress accept it, which makes it ideal for a website. Some older software and some official portals do not accept it yet.
- PNG: lossless and able to keep transparency. Perfect for a logo or a screenshot, but too heavy for a photo.
What about HEIC? It has been the iPhone's photo format since 2017. It is very efficient, but Windows and most browsers cannot open it. The good news: when you choose your photos on the iPhone itself, it converts them to JPEG automatically.
The information hidden in your photos
Besides the image itself, every photo carries metadata, known as EXIF: the date and time it was taken, the phone model, the camera settings and, very often, the exact GPS coordinates of the place.
That is handy for sorting your memories, much less so once the photo leaves your phone. A photo of your living room in a classified ad, or sent as an e-mail attachment, can reveal your home address to anyone who knows how to read this data. The big social networks usually strip the location when you post, but e-mail, websites and some sharing services keep it.
The tool rebuilds each photo from the image alone: the new versions contain none of this information. The “GPS location removed” badge tells you which photos had one.
Key takeawayOn screen, a photo doesn't need 12 million pixels: resizing and then compressing it divides its file size by about 10, with no visible loss. Keep the original for printing.
Words to know
- Pixel
- The smallest coloured dot in a digital image. A 4000 × 3000 pixel photo contains 12 million of them.
- KB and MB
- Units of file size: 1 megabyte (MB) equals 1000 kilobytes (KB). A phone photo weighs 3 to 5 MB, a photo ready for e-mail about 300 KB.
- Lossy compression
- A method that makes a file lighter by removing the least visible details. Used by JPEG and WebP, it cannot be undone.
- Lossless compression
- A method that makes a file lighter without changing the image at all. Used by PNG, it saves far less space on a photo.
- WebP
- A recent image format, 25 to 35% lighter than JPEG, designed for websites.
- HEIC
- The default photo format on iPhones. Efficient, but poorly supported by Windows and most browsers.
- EXIF
- Information hidden in a photo: date, camera model, settings and often the GPS location.
Module 2
Shrinking your photos step by step
Choose your photos
- Open the Compress photos tool.
- Click Choose photos, or drag them straight into the box from a folder on your computer.
- On a phone, the button opens your photo gallery.
- You can process up to 30 at once, in JPEG, PNG, WebP and other formats.
- The work starts right away, on your device: nothing is sent over the Internet.
TipOn an iPhone, open the tool on the phone itself: your HEIC photos will be converted automatically.
Say what the photos are for
Under “What are they for?”, click the card that matches your need:
- E-mail: 1600 pixels, good quality, very light;
- Website: 1920 pixels, in WebP format;
- Social networks: 2048 pixels, high quality;
- Online form: under 1 MB per photo.
You can switch to another use at any time: the photos are recalculated automatically.
Screenshot : Compress photos Fine-tune with the detailed settings
- For a special need, open Detailed settings.
- You will find four settings: Size (long side), from 800 px to 3840 px or “Original size”; Format (JPEG, WebP or PNG); Quality, from 40 to 95; and Maximum weight, from “No limit” to 5 MB.
- As soon as you change a setting, the tool switches to custom mode and recalculates.
- A short note under the settings reminds you what the chosen format is good for.
TipA website asks for “500 KB maximum”? Choose 500 KB under Maximum weight: the tool finds the best quality under that limit.
Read the result
- Each photo appears in the list with its dimensions and file size before → after, for example “4032 × 3024 · 4.2 MB → 1600 × 1200 · 310 KB”.
- A badge shows how much you saved (for example “−93%”).
- The “GPS location removed” badge flags a photo that contained the place where it was taken.
- If a photo was already light, the tool leaves it as it is and says so: “Already light: kept as is”.
- At the top of the list, the total sums up the starting and final file sizes.
Screenshot : Compress photos Compare before and after
- To check the quality, click the Compare before / after button to the right of the photo.
- A window opens: drag the slider, or the image itself, to see the original on one side and the lighter version on the other.
- Tick Actual size (see details) to look at the pixels up close.
- If the difference bothers you, raise the quality in the detailed settings.
Get your photos
You have three options:
- the Download button next to a photo, to save just that one;
- Download all (.zip), to get every photo in a single compressed file;
- on a phone, Share, to send them straight to a messaging or e-mail app.
The new photos keep their original name followed by “-small”, for example
birthday-small.jpg: your originals are never changed. Remove all clears the list.TipOn Windows, right-click the .zip file and choose “Extract All” to get your photos out.
All done: over to you.
Module 3
Practical cases
Sending photos of the association's party
Martine wants to e-mail 20 photos of the spring party held by “Les Jardins de Clara”, a community garden association. Together they weigh 80 MB, and her e-mail service refuses to send them.
She picks the 20 photos, keeps the E-mail use, then clicks Download all (.zip). Each photo now weighs about 300 KB: the total drops to 6 MB and fits in a single message. Along the way, the GPS locations, which pointed to a member's garden, have disappeared.
Faster pages for a holiday cottage website
The “Gîte des Trois Épis”, a holiday cottage, shows 25 bedroom photos on its WordPress site. On a phone using 4G, the page takes several seconds to appear.
The owner runs his photos through the Website use: 1920 pixels in WebP format. He replaces the old images in the WordPress media library. The page becomes much lighter, visitors wait less, and Google, which measures page speed, takes note. He can check the result with the complete website diagnosis.
A document rejected by an online form
For an insurance claim, Paul's insurer asks for a photo of an invoice, “1 MB maximum”. His photo weighs 3.8 MB and the site rejects it.
He chooses the Online form use. The tool finds the best possible quality under 1 MB and reduces the size slightly if needed. With Compare before / after and Actual size, Paul makes sure the amounts are still readable, then uploads his photo.
Common mistakes
- Overwriting or deleting the original: lossy compression cannot be undone, so always keep the original photo.
- Printing a photo compressed for the screen: for a paper print, start again from the original at its original size.
- Choosing PNG for a photo: the file stays heavy, so keep this format for logos and screenshots.
- Setting the quality too low: below 60, flaws appear, so check with Compare before / after.
- Posting a photo taken at home without removing its metadata: the GPS location can reveal your address.
The essentials
- The number of pixels and the file size in KB or MB are two different but linked things.
- For screens, 1600 to 2048 pixels are enough: resizing and compressing divides the file size by about 10.
- JPEG for sharing anywhere, WebP for a website, PNG for logos and screenshots.
- Photos made lighter by the tool no longer contain the GPS location or any other hidden information.
- Everything happens in your browser: your photos are never sent anywhere.
Test yourself
A few questions to check that everything is clear.