Cobalt Screen
A full-screen solid cobalt color (#0047AB). Fill your whole display, or download the cobalt screen as an image in 480p, 720p, 1080p, 1440p, 4K or any size you type in.
Advanced — print resolution (DPI)
What is a cobalt screen?
A cobalt screen is simply a web page filled edge to edge with one solid color — Cobalt, hex #0047AB, or rgb(0, 71, 171). It is a dark, cool color: in HSL it sits at 215° hue, 100% saturation and 34% lightness, and its relative luminance is 7.4%. The closest standard CSS color is Dark Slate Blue (#483D8B).
Turning a display into a single flat color is more useful than it sounds — as a light source, a test pattern, a video or photo backdrop, or ambient lighting. This page is that color, ready to open full screen or download, with no app to install and nothing uploaded anywhere.
What people use a cobalt screen for
Blue screens are the standard for bias lighting — a dim blue or blue-white glow placed behind a monitor or TV lowers the perceived contrast of the room and eases eye strain during long sessions. Blue is also the reference for checking the blue sub-pixels of a panel, a favourite for "blue screen" jokes, and a moody backdrop for photography and streams.
Beyond that, a cobalt screen is handy for all the things any solid-color screen is good for:
- Checking an LCD for backlight bleed and IPS glow, or an OLED for stuck "always-on" pixels — faults hide in a dark field.
- Spotting dust, smudges and scratches on a monitor, phone or TV before cleaning it.
- Bias or ambient lighting — running a second screen or an old phone as a soft cobalt glow behind a desk or TV.
- A clean, distraction-free background for video calls, screen recordings, live streams and product photos.
- A backdrop or placeholder for digital signage, kiosks, stage screens and mock-ups.
- Judging screen brightness, white balance and how evenly a panel lights up.
#0047AB) shown full-frame. This same image is generated automatically as the share preview when you post the cobalt screen to Pinterest, Facebook or X — no manual upload needed. Open it full screen above, or download it in 1080p, 4K or a custom size.How to use the cobalt screen
- The color is already set to Cobalt (
#0047AB). Use the color box or hex field above if you want to nudge it. - Pick a resolution — tap 480p, 720p, 1080p, 1440p or 4K, choose an aspect ratio, or type an exact width and height.
- Preview — the panel shows the exact pixel size and color you will get.
- Open full screen — tap the button or the preview and your entire display fills with cobalt. Press Esc or tap the screen to exit.
- Download — tap Download PNG or Download JPG to save a cobalt image at the size you chose.
- Share — the share buttons post this exact cobalt screen, with a matching preview image, to Pinterest, Facebook, X, Reddit, WhatsApp and more.
Cobalt screen resolutions
Every preset produces a clean, exact cobalt image — a solid color compresses to a tiny file even at 4K. The presets below are 16:9; switch the aspect ratio for 16:10, 21:9 ultrawide, 4:3, 3:2, square (1:1) or 9:16 portrait, or use Fit my screen to match your device exactly.
| Name | Pixels (16:9) | Best for |
|---|---|---|
| 480p | 854 × 480 | SD — small previews, quick tests |
| 720p | 1280 × 720 | HD — laptops, older monitors, video calls |
| 1080p | 1920 × 1080 | Full HD — the most common desktop and TV size |
| 1440p | 2560 × 1440 | QHD — high-resolution monitors |
| 2160p (4K) | 3840 × 2160 | Ultra HD — 4K TVs and monitors |
Need something else? Type any width and height up to 16384 px — common choices are 1080 × 1920 for phones, 1080 × 1080 for social posts and 3840 × 2160 for 4K TVs. The Advanced panel adds a real DPI value to the PNG for print.
How to download the cobalt screen
Set the size you want, then tap Download PNG for a lossless file (best for a flat color) or Download JPG for maximum compatibility. The image is generated in your browser and saved straight to your device as cobalt-screen-WIDTHxHEIGHT.png — nothing is uploaded, there is no watermark, and it is free to use for wallpapers, backgrounds, video, signage or print.
Using a cobalt screen on any device
Phone & tablet — open this page in your browser and tap Open full screen; on iPhone and iPad, turn the auto-lock off first if you want it to stay on, and hide the browser bars by tapping full screen. Laptop & desktop — full screen hides the taskbar and menu bar for a true edge-to-edge cobalt field; move the window to a second monitor first if you are using it as bias lighting. TV & projector — open the page in the built-in browser, or download the 4K image and open it from a USB stick or a casting app for a rock-steady cobalt screen.
Cobalt screen color codes
The full-screen color and every download use exactly these values. Tap any row to copy it.
Contrast against white text 8.44:1 · against black text 2.49:1. See the full Cobalt color page for harmonies, shades and tints, or open it in the color picker.
Popular color screens
The colors people reach for most often as a full-screen background or light:
Colors similar to Cobalt
More blue screens
Cobalt screen — FAQ
What is the hex code for a cobalt screen?
A cobalt screen uses the color Cobalt, hex #0047AB — rgb(0, 71, 171). The full-screen view and every download use exactly that value. The nearest standard CSS name is Dark Slate Blue (#483D8B).
How do I make my whole screen cobalt?
Open this page and tap Open full screen (or tap the preview). Your browser fills the entire display with cobalt and hides its own toolbars. Press Esc, or tap the screen, to come back. It works on phones, tablets, laptops, desktops and most smart-TV browsers.
Can I download the cobalt screen in 1080p or 4K?
Yes. Tap a resolution preset — 480p, 720p, 1080p, 1440p or 4K (3840 × 2160) — or type any custom width and height, then tap Download PNG or Download JPG. A solid cobalt image stays a very small file even at 4K.
Is the cobalt screen free to use?
Completely. There is no sign-up, no watermark and no limit. The image is created in your browser and never uploaded, so you can use the cobalt screen for wallpapers, video backgrounds, streaming, signage, photography or print at no cost.
Does a cobalt screen save battery?
On phones and laptops with an OLED or AMOLED display, yes — dark pixels use very little power and true black uses none, so a cobalt screen draws less than a bright one. On a normal LCD the backlight stays on regardless, so the saving is small.