IMAGE GUIDE
Image Resolution vs. File Size
Image resolution and file size are closely related, but the relationship is not always obvious. Reducing the pixel dimensions of an image can dramatically reduce its file size because there is simply less data to store.
Pixels add up quickly
A 4032 × 3024 pixel photograph contains about 12.2 million pixels. That is a useful amount of detail for printing or heavy editing, but it is usually far more than needed for a website, email, or social media post.
Reducing the same image to 1200 × 900 pixels leaves about 1.1 million pixels — less than one tenth of the original. The resulting file is often much smaller, even before adjusting compression quality.
Real QuakeStar measurements
We took a 4032 × 3024 camera JPEG and resized it to several common dimensions using QuakeStar's Image Resizer. The output quality was set to 85% JPEG.
| Max dimensions | Actual dimensions | File size |
|---|---|---|
| Original | 4032 × 3024 | 5.03 MB |
| 1920 × 1440 | 1920 × 1440 | 222.9 KB |
| 1200 × 900 | 1200 × 900 | 70.6 KB |
| 800 × 600 | 800 × 600 | 31.8 KB |
Going from the original 4032 × 3024 image to 1200 × 900 reduced the file from 5.03 MB to about 70.6 KB — a reduction of roughly 98.6%.
Resize before you compress aggressively
One common mistake is to keep a huge image and then crank the JPEG quality down to make the file small. A better approach is usually to resize first, then use moderate quality.
For example, a 4032 × 3024 image saved at very low JPEG quality might still be larger than a 1200 × 900 version saved at higher quality, and the smaller version will usually look better on screen.
How to choose dimensions
- Website hero images: often 1920 px on the longest side.
- Inline photos: usually 800–1600 px wide, depending on layout.
- Email: 600–1200 px wide is usually plenty.
- Thumbnails: 200–400 px wide.
Keep the original
Resizing removes pixel information permanently. If you later need the full-resolution version, you cannot recover it from a small copy. Always keep your original camera file or master image.