4K Resolution Calculator

4K Resolution Guide

1) What 4K resolution means

“4K” is a label, but this calculator uses exact pixel dimensions. UHD 4K is 3840×2160, which equals 8,294,400 pixels (8.294 MP). DCI 4K is 4096×2160, which equals 8,847,360 pixels (8.847 MP). Switching presets updates totals and aspect ratio instantly.

2) UHD versus DCI 4K

UHD targets consumer displays and stays 16:9. DCI 4K is wider, with 256:135 (about 1.896:1). This affects composition, cropping, and letterboxing. The calculator simplifies the ratio by dividing both sides by the greatest common divisor.

3) Megapixels for images and screenshots

Megapixels are total pixels divided by 1,000,000. A UHD still holds about 8.3 MP, while a 1080p still holds 2.074 MP. That is a 4× jump in pixel count, which can raise storage needs and editing load. For photos, megapixels also influence print sizing and how far you can crop without softening detail.

4) Scaling compared with 1080p

For UHD 4K, width scaling is 3840/1920 = 2× and height scaling is 2160/1080 = 2×. Area scaling becomes 4×. Use these factors to estimate render cost, export time, and how much detail you gain when downsampling to 1080p.

5) PPI and pixel pitch on real screens

Entering a diagonal size enables PPI using √(width² + height²) ÷ diagonal inches. Example: a 27-inch UHD panel is roughly 163 PPI, so pixel pitch is near 0.156 mm (25.4 ÷ PPI). A 55-inch UHD TV is about 80 PPI, with pitch near 0.317 mm. Higher PPI usually looks sharper at the same distance.

6) Refresh rate, color depth, and chroma

Throughput depends on resolution, refresh, and bits per pixel. A simple estimate is: pixels × refresh × (bpc × 3 × chromaFactor). UHD at 60 Hz, 8 bpc, 4:4:4 is about 11.94 Gbps for active pixels, and about 14.33 Gbps with 20% overhead. Using 10 bpc increases that estimate further. Add overhead to model margin.

7) Practical workflow checks

Use Custom for unusual formats like 5120×2160 ultrawide or camera rasters. Compare presets to decide whether you need UHD, DCI, or a crop. If you must match a delivery spec, verify the aspect ratio and total pixels first. Export CSV or PDF so your planning notes match the computed figures exactly, in real projects too.

FAQs

1) Is UHD 4K the same as DCI 4K?

No. UHD 4K is 3840×2160 with a 16:9 shape. DCI 4K is 4096×2160 and is wider. They have different pixel totals and different aspect ratios, so cropping or letterboxing may be needed.

2) Why does the calculator show an overhead percentage?

Many links and video standards include blanking, encoding, or timing overhead beyond active pixels. The overhead setting adds a planning margin to the raw bitrate estimate. It is not a guarantee of any specific interface limit.

3) What does chroma 4:2:0 change in the bandwidth estimate?

Chroma subsampling reduces color sampling compared with 4:4:4. The calculator applies a lower chroma factor, which reduces estimated bits per pixel and the resulting bitrate. It helps compare workflows like editing, playback, and capture.

4) How is PPI calculated when I enter diagonal size?

It uses the pixel diagonal √(width² + height²) divided by the screen diagonal in inches. That produces pixels per inch. Pixel pitch is then 25.4 divided by PPI, reported in millimeters.

5) Does a higher refresh rate always require more bandwidth?

In this estimate, yes. Bitrate scales linearly with refresh rate because more frames are sent each second. Going from 60 Hz to 120 Hz roughly doubles the computed throughput, assuming the same resolution and color settings.

6) Can I use Custom for phone or camera resolutions?

Yes. Choose Custom and enter the exact width and height in pixels. The calculator will still compute megapixels, aspect ratio, scaling, and optional PPI. This is useful for non-standard rasters and sensor readouts.