A job application, a school portal or an insurance claim asks for a photo "under 1 MB", and the one on your iPhone is several megabytes. Or an email bounces because the attachments are too big. This guide explains what makes a photo file big and the three ways to shrink one, then shows how to do it with Convert Cat, our photo and PDF converter for iPhone and iPad.
What makes a photo file big
Two things decide the size of a photo file:
- Pixels. A photo from the camera has millions of them, often more than an upload form or an email needs. Fewer pixels means a smaller file.
- Quality (compression). JPEG and HEIC throw away fine detail to save space. Lower quality means a smaller file, and at some point you will see the difference.
So there are three ways to get a smaller file: lower the quality, cut the pixels, or ask for a size and let the app find a mix of both. Convert Cat lets you do all three.
Get a photo under a size limit
This is the quickest way when a form gives you a limit.
- Open Convert Cat and tap Choose Photos. Pick one photo or as many as you like. For photos in iCloud Drive or Files, tap Choose Files.
- Tap Make smaller ("Under a size, like 1 MB, or by quality").
- Under Target size, pick a limit: 100 KB, 200 KB, 500 KB, 1 MB, 2 MB or 5 MB. If your form says something else, type it next to Under and choose KB or MB.
- Tap Compress. The button counts your photos, such as Compress 5 Photos.
Each photo is made as sharp as it can be while staying under the size. If quality alone isn't enough, it gets fewer pixels. The size isn't a guess: Convert Cat checks each finished file against your limit. If a photo still can't get under your limit, the result tells you so and saves the smallest version it made.
Lower the quality instead
If there's no exact limit and you only want lighter files, tap Quality next to Target size on the Make smaller screen. Move the slider toward the tortoise for smaller files or the sparkles for sharper ones; the label beside it reads Best, High, Medium, Low or Smallest. The panel at the top shows about how big the files will be, worked out from your photos.
Quality is a trade. The lower you go, the more detail is lost, so check the result before you send it. PNG ignores quality: for PNG files, use a target size or resize instead.
Resize to fewer pixels
Sometimes the limit is in pixels, not megabytes, or you just want a photo sized for the place it's going. Tap Resize ("Email, social, percent or exact pixels") and choose under Pixels:
- Email: 1600 px long side
- Instagram: 1080 px long side
- Full HD: 1920 px long side
- Messages & web: 1280 px long side
- Small: 800 px long side
- Custom: by percent, by long side, or exact width and height
With a long-side size, smaller photos are never enlarged. With exact pixels, if the shape is different, the photo fills the frame and the edges are trimmed evenly; nothing is stretched. Then tap Resize, such as Resize 3 Photos.
You can combine the two. Under More options, Make smaller also lets you set the pixels and the format, and Resize lets you set a target size. HEIC is often smaller than JPEG, but for Windows, email or websites, JPEG is the safe choice.
Check, save and send
The result shows the size before and after, how much smaller the files got, and "originals untouched". Tap a file to look at it before you send it. Then tap Save to Photos, Save to Files or Share.
Convert Cat works on copies, so your originals in Photos and Files are never changed, and Save to Photos adds the smaller photos next to them. Make smaller and Resize remember your last settings, so the same job next time is quick.
One more thing to check before you tap Compress or Resize: Hidden photo info, further down the same settings screen. Photos can carry where they were taken (GPS), the date and the phone or camera. The first time, it's set to Remove location & photo info, which the app marks "Recommended for sharing".
Got a HEIC file the form won't take?
Some upload forms reject iPhone HEIC photos whatever their size. Make smaller saves JPEG unless you change the format, but if you only need a different format, see how to convert HEIC to JPG on iPhone. Note that a JPEG made from a HEIC is often bigger, not smaller.
What it costs
Everything in this guide is free: target sizes, quality, resizing and removing photo info, for as many photos as you pick. There's no watermark, no ads, no subscription and no account. Convert Cat Pro is an optional, one-time unlock (the App Store shows the price). It adds Saved presets, Name your files, Shortcuts and Convert from the share sheet. More on the Convert Cat page.
Quick answers
How do I make a photo under 1 MB on iPhone?
In Convert Cat, tap Choose Photos, then Make smaller, pick 1 MB under Target size and tap Compress.
Can I make it under 200 KB, or a size that isn't listed?
Yes. Tap 200 KB, or type any size next to Under and pick KB or MB.
Will the smaller photo look worse?
It can. A smaller file has less detail or fewer pixels. Convert Cat keeps each photo as sharp as it can under your size, and you can tap a file to look at it before you send it.
Does it change my original photo?
No. Convert Cat works on copies.
Can I shrink many photos at once?
Yes. Pick as many as you like; the size limit applies to each photo.
Try Convert Cat
Try Convert Cat: free, no watermark, no sign-up → iyio.com/apps/convert-cat