What exactly is 4K resolution?

In consumer displays and common 16:9 video workflows, 4K UHD means 3840 pixels wide by 2160 pixels tall (8,294,400 total pixels). The term “4K” approximates the horizontal sample count. The DCI digital-cinema 4K container is up to 4096 × 2160, so the context matters.

What bitrate should I use for 4K?

Bitrate depends on frame rate, codec, content and delivery platform. For a fixed 40 Mbps example, one hour is about 18 GB before audio and container overhead. Use the current requirements of the destination platform rather than treating one bitrate as universal.

How much storage does one hour of 4K video take?

Resolution alone does not determine storage. At a user-selected 40 Mbps, 40 × 3,600 ÷ 8 ÷ 1,000 = 18 decimal GB before audio and container overhead. Enter the actual video bitrate and duration for your file.

What is the PPI of a 27-inch 4K display?

A 3840 × 2160 panel with a 27-inch diagonal is approximately 163.2 pixels per inch. PPI describes pixel density; perceived sharpness also depends on viewing distance and eyesight.

What is the difference between 4K UHD and DCI 4K?

The UHD image format is 3840 × 2160 at 16:9. The DCI digital-cinema specification supports a 4K decoder output up to 4096 × 2160; that full container is 256:135, approximately 1.90:1. A camera, file or display may support one or several formats, so inspect its actual dimensions.

How does 4K compare to 1080p in file size?

4K has exactly four times the pixels of 1080p, but that does not make every encoded file four times larger. File size is determined mainly by bitrate and duration: size in bytes is bitrate in bits per second multiplied by seconds, divided by eight.

Does 3840 × 2160 automatically mean HDR?

No. Resolution and dynamic range are separate properties. A 3840 × 2160 file or display can be SDR or HDR, with different bit depths, transfer functions and color metadata.

4K Resolution Reference

4K UHD is 3840 × 2160 pixels (8,294,400 pixels, 16:9). Calculate aspect ratio, megapixels, PPI and video storage for any dimensions.

Resolution

3840 x 2160

pixels (W x H)

Total Pixels

8,294,400

per frame

Aspect Ratio

16:9

widescreen

Standard Name

4K UHD

Ultra High Definition

Resolution, PPI & File Size Calculator

Preloaded with 3840 × 2160. Change any value to analyze another display or video.

Width (px)

Height (px)

Diagonal (in)

Bitrate (Mbps)

Duration (minutes)

Aspect ratio

Total pixels

Megapixels

Pixel density

Video size (decimal)

File size uses bitrate × duration ÷ 8 and excludes small container/audio overhead.

Pixel Density Calculator

Enter the diagonal screen size to find the PPI of a 4K UHD display.

inches

Common 4K Screen Sizes

Screen Size	PPI
24 in	184 PPI
27 in	163 PPI
32 in	138 PPI
43 in	102 PPI
55 in	80 PPI
65 in	68 PPI

YouTube Upload Bitrates

Official YouTube upload recommendations checked September 2026. These are not universal streaming or camera-recording rates.

Use Case	Bitrate
2160p SDR, 24/25/30 fps	35 – 45 Mbps
2160p SDR, 48/50/60 fps	53 – 68 Mbps
2160p HDR, 24/25/30 fps	44 – 56 Mbps
2160p HDR, 48/50/60 fps	66 – 85 Mbps

Source: YouTube recommended upload encoding settings. YouTube re-encodes uploads.

File Size Estimates — 4K UHD

Decimal storage examples from bitrate × seconds ÷ 8. Resolution and frame rate do not determine size without a bitrate or codec setting.

Bitrate	1 min	10 min	1 hour
20 Mbps	~150 MB	~1.5 GB	~9 GB
40 Mbps	~300 MB	~3 GB	~18 GB
60 Mbps	~450 MB	~4.5 GB	~27 GB
100 Mbps	~750 MB	~7.5 GB	~45 GB
800 Mbps	~6 GB	~60 GB	~360 GB

Resolution Comparison

How 4K UHD stacks up against other common standards.

Standard	Width	Height	Total Pixels	vs 4K	Label
480p (SD)	854	480	409,920	0.05x	SD
720p (HD)	1280	720	921,600	0.11x	HD Ready
1080p (FHD)	1920	1080	2,073,600	0.25x	Full HD
1440p (QHD)	2560	1440	3,686,400	0.44x	Quad HD
4K (UHD)	3840	2160	8,294,400	1x	Ultra HD
DCI 4K (Cinema)	4096	2160	8,847,360	1.07x	DCI 4K
8K (UHD-2)	7680	4320	33,177,600	4x	8K UHD

UHD and DCI Facts

Consumer UHD frame: 3840 × 2160
Aspect ratio: 16:9
Total samples / pixels: 8,294,400
DCI 4K maximum container: 4096 × 2160
DCI 4K container ratio: 256:135 (~1.90:1)
Pixels vs 1080p: Exactly 4×
Each axis vs 1080p: Exactly 2×
Resolution implies HDR?: No
Resolution fixes bitrate?: No
PPI needs screen diagonal?: Yes
File size needs bitrate?: Yes
Display label: 4K UHD / Ultra HD

Standards and Current References

SMPTE ST 2036-3 identifies the 3840 × 2160 UHDTV image format.
DCI Digital Cinema System Specification 1.4.2 defines a 4K decoder output up to 4096 × 2160.
YouTube resolution guidance lists 2160p (4K) as 3840 × 2160 for its 16:9 workflow.
YouTube upload guidance is the source for the SDR/HDR bitrate examples above; destination requirements can change.

Copy Spec Snippet

Click any row to copy the spec to your clipboard.

Resolution 3840 x 2160 px

Total pixels 8,294,400 pixels

Aspect ratio 16:9

Common name 4K UHD / Ultra HD

Summary