What DPI Should an Image Be for Screen? (The Honest Answer)
Someone told you to save at 72 DPI for the web. That advice is decades out of date, and DPI does not affect how your image looks on a screen at all. Here is what actually matters.
The one-sentence answer
For anything shown on a screen, DPI is irrelevant — only the pixel dimensions matter. A 1920×1080 image looks identical whether its DPI tag says 72, 96 or 300.
Why the 72 DPI myth exists
The original 1984 Macintosh display packed 72 pixels into every physical inch, so one inch in a document equalled 72 pixels on screen. That convenient coincidence became a rule people repeated for forty years. Modern displays run at anything from 96 to over 450 pixels per inch, and none of them read the DPI tag inside your file. The browser draws pixels, full stop.
What DPI is my computer screen? (Monitor DPI vs screen resolution)
Two different numbers get called “screen DPI”. The physical one is pixels per inch (PPI): how tightly a monitor packs its pixels. The logical one is the scaling setting in Windows, which treats one logical inch as 96 pixels at 100% scaling, 120 at 125% and 144 at 150%. Neither reads the DPI tag inside your image file.
To work out your monitor's physical PPI:
- Find the resolution in pixels (Windows: Settings › System › Display; Mac: Apple menu › About This Mac › Displays).
- Get the diagonal in pixels: √(width² + height²).
- Divide by the advertised screen size in inches.
| Screen | Resolution | Diagonal in pixels | PPI |
|---|---|---|---|
| 24-inch 1080p monitor | 1920 × 1080 | 2,203 | 91.8 |
| 27-inch 1440p monitor | 2560 × 1440 | 2,937 | 108.8 |
| 32-inch 4K monitor | 3840 × 2160 | 4,406 | 137.7 |
| 15.6-inch 1080p laptop | 1920 × 1080 | 2,203 | 141.2 |
| 27-inch 4K monitor | 3840 × 2160 | 4,406 | 163.2 |
| 14-inch 2880 × 1800 laptop | 2880 × 1800 | 3,396 | 242.6 |
Same resolution, different DPI: 1920 × 1080 is 91.8 PPI on a 24-inch monitor but 141.2 PPI on a 15.6-inch laptop, which is why the laptop looks sharper and its text smaller. That is the whole “DPI vs screen resolution” difference — resolution counts pixels, PPI measures how small they are.
Sources: PPI formula and the 27-inch 4K example (163 PPI) from Wikipedia, “Pixel density”; Windows 96, 120 and 144 DPI settings from Microsoft Learn, “DPI and device-independent pixels”.
What the DPI number actually does
DPI is a note stored in the file's metadata that says "when printed, lay this many pixels down per inch of paper". It changes the printed size, not the picture. Change 300 to 150 and the same image prints twice as wide and half as sharp — while looking exactly the same on your monitor. The mechanics are covered in DPI vs PPI, and you can edit the tag itself with the change image DPI tool.
What to actually specify for screens
| Use | Pixel width to export | Notes |
|---|---|---|
| Full-width hero banner | 1920–2560 px | 2560 covers most laptops at 2× scaling |
| Blog post image | 1200–1600 px | Comfortably sharp on retina screens |
| Product photo | 1500–2000 px square | Leaves room for zoom |
| Thumbnail | 400–600 px | Keep under 60 KB |
| Email image | 600 px | Standard email body width |
| Presentation slide | 1920×1080 px | Matches 1080p projection |
Resize to any of these in seconds with the image resizer.
The retina factor — the one real complication
High-density screens draw two or three physical pixels for every CSS pixel. A logo displayed 300 px wide on a 3× phone screen needs a 900 px source file to look crisp. The practical rule: export images at roughly twice the size they will be displayed, then compress harder to keep the bytes down. Losing 10% of quality to compression is invisible; being short on pixels is immediately obvious.
What to optimise instead of DPI
- File size. Aim under 200 KB for most web images — see compressing images for a website.
- Format. WEBP for photographs on the web, PNG for graphics with hard edges, JPG for maximum compatibility. Compare them in WEBP vs JPG.
- Dimensions. Never ship a 6000 px camera file to display it at 800 px.
- Colour profile. Save as sRGB or colours shift in some browsers — details in sRGB vs Adobe RGB.
But my client insists on 72 DPI
Give it to them — it costs nothing and changes nothing visible. Set the tag with the DPI tool and export at the correct pixel dimensions. Everybody wins.
Quick reference
- Screen: DPI does not matter. Pixel dimensions do.
- Print: DPI matters a great deal — see 300 DPI vs 150 DPI.
- Retina: export at roughly 2× the display size.
- Sizing a print? Use the DPI and print size calculator.
Frequently Asked Questions
What DPI is a computer screen?
Physically, most desktop monitors are about 90 to 165 pixels per inch: a 24-inch 1080p monitor is 91.8 PPI and a 27-inch 4K monitor 163.2. Windows separately uses a logical 96 DPI at 100% scaling, 120 DPI at 125% and 144 DPI at 150%.
How do I calculate my monitor's DPI?
Take the diagonal in pixels — the square root of width² + height² — and divide it by the screen's diagonal in inches. A 27-inch 2560 × 1440 monitor is about 2,937 pixels corner to corner, so 2,937 ÷ 27 = 108.8 PPI.
Is screen resolution the same as DPI?
No. Resolution is the pixel count (for example 1920 × 1080); DPI or PPI is how tightly those pixels are packed. The same 1920 × 1080 is 91.8 PPI on a 24-inch monitor and 141.2 PPI on a 15.6-inch laptop.
What DPI should an image be for a screen?
Any — the DPI tag is ignored on screens. Export the pixel dimensions the image is displayed at, about twice that for high-density screens, and leave the DPI value at whatever your editor sets.
Gear we recommend for this workflow
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Want to know what your own file is set to? The image DPI checker reads the stored DPI and shows how large the picture prints sharply at 300 DPI.