How do I know if my video is 4K?
Open it and check the size in Video. 3840 × 2160 (or 2160 × 3840 in portrait) is 4K UHD and 4096 × 2160 is DCI 4K. Anything smaller, such as 2560 × 1440, is not 4K even if the camera or file name says so.
Free · runs in your browser
Check a video’s resolution and find out if it is really 4K
See the exact pixel size of any video, the name it goes by, and the details that make a file look different from what its numbers say.
To check a video’s resolution, open it here and read the size at the top of the Video section: the width and height in pixels, matched against common sizes such as 1080p, 4K UHD or DCI 4K. A 4K UHD file measures 3840 × 2160; anything smaller is not 4K, whatever the file name or upload page says.
The checker also shows the details a single number hides: the coded size the encoder actually stored, the size a player displays, the pixel aspect ratio of anamorphic footage, and whether the file carries a rotation flag that turns landscape pixels into a portrait picture. It works for MP4, MOV, MKV, WebM, AVI and camcorder formats.
Your video is read in the browser and never uploaded. Resolution is only half of picture quality, so the same page also shows the bitrate; the bitrate checker explains how to read it.
How to check the resolution of a video
Open your video
Drop it on Drop a video or photo here, press Open a file (Ctrl/Cmd+O) or paste it (Ctrl/Cmd+V). Try the sample video shows the page in action.
Read the size and its name
The Video section opens first. It gives the width × height in pixels and the nearest common name (720p, 1080p, 4K UHD, 8K and so on), with an aspect-ratio frame drawn to scale.
Check coded size and pixel aspect
If the coded size differs from the displayed size, or the pixels are not square, both values are listed. The ⓘ next to each explains what it means for your file.
Look for a rotation flag
Phone videos often store landscape pixels with a rotation flag. The checker shows the rotation flag next to the size, so you can tell which way the picture will play.
Judge quality with the bitrate
Scroll down in Video to the bitrate and the bitrate-over-time graph. A “4K” file with a very low bitrate rarely holds 4K detail.
Resolution names and the pixels behind them
Resolution names are shorthand. “1080p” refers to the height in pixels and the “p” to progressive scan; “4K” refers, roughly, to the width. The table lists the sizes you will meet most often.
| Name | Pixels (width × height) | Megapixels per frame | Where you meet it |
|---|---|---|---|
| SD (PAL) | 720 × 576 | 0.4 | DVDs and broadcast in PAL regions (stored anamorphic, see below) |
| SD (NTSC) | 720 × 480 | 0.35 | DVDs and broadcast in NTSC regions |
| 720p (HD) | 1280 × 720 | 0.9 | Older phones, webcams, some broadcast |
| 1080p (Full HD) | 1920 × 1080 | 2.1 | The most common size for phones, laptops and online video |
| 1440p (QHD) | 2560 × 1440 | 3.7 | Gaming captures and screen recordings |
| 2.7K | 2704 × 1520 | 4.1 | Action cameras |
| 4K UHD | 3840 × 2160 | 8.3 | Phones, consumer cameras, TVs and streaming |
| DCI 4K | 4096 × 2160 | 8.8 | Cinema cameras and digital cinema projection |
| 8K UHD | 7680 × 4320 | 33.2 | High-end phones and cameras |
What is the resolution of 4K video?
For TVs, phones and online video, 4K means 4K UHD: 3840 × 2160, exactly four times the pixels of 1080p. Cinema uses DCI 4K: 4096 × 2160, slightly wider. Both count as 4K; a file that is 2560 × 1440 or 2704 × 1520 does not, even if it was exported from a “4K” camera.
Portrait sizes
A vertical phone video is often listed as 1080 × 1920 or 2160 × 3840: the same number of pixels as 1080p or 4K, turned on its side. The checker compares it against the same common sizes, so a 2160 × 3840 clip still counts as 4K.
Coded size, display size and pixel aspect ratio
Three different sizes can live in one file, and tools that show only one of them disagree with each other for that reason.
- Coded size is what the encoder actually compressed. H.264 works in 16 × 16 pixel blocks, so a 1080-line video is usually coded as 1088 lines with the extra 8 cropped away on playback. You may see 1920 × 1088 in some tools; the picture is still 1080p.
- Display size is what a player shows after cropping and after correcting for pixel shape. This is the number that matters for “is it 1080p or 4K”.
- Pixel aspect ratio (also called sample aspect ratio) is the shape of each pixel. Most modern video has square pixels (1:1). Older and professional formats squeeze a wide picture into fewer columns: HDV records 1440 × 1080 with pixels 4:3 as wide as they are tall, which plays back as 1920 × 1080, and PAL DVD stores 720 × 576 that displays as 4:3 or 16:9 depending on its flags.
| What the file stores | Pixel aspect | What you see |
|---|---|---|
| 1920 × 1088 coded, cropped to 1080 | 1:1 | 1920 × 1080, 16:9 |
| 1440 × 1080 | 4:3 | 1920 × 1080, 16:9 |
| 720 × 576 (PAL DVD, widescreen) | 64:45 | 1024 × 576, 16:9 |
| 720 × 480 (NTSC DVD, widescreen) | 32:27 | About 853 × 480, 16:9 |
| 1920 × 1080 with a 90° rotation flag | 1:1 | 1080 × 1920 portrait |
Rotation deserves a word. Phones record with the sensor in one orientation and add a rotation flag saying how to turn the picture for playback. Players that honour the flag show a portrait video; those that ignore it show it sideways. The checker lists the flag alongside the size so you can tell which situation you are in.
Resolution is not the same as quality
A “video quality checker” that reports only resolution tells half the story. Detail depends on how many bits the encoder had to describe those pixels, how much the picture moves, the codec, and what happened to the file before it reached you. A 4K file at a starved bitrate can look softer than a well-encoded 1080p one.
For a sense of scale, YouTube’s recommended upload settings (checked on 7 November 2026) suggest 35–45 Mbps for 4K SDR at 24–30 frames per second and 8 Mbps for 1080p. If a supposedly 4K download runs at a few megabits per second, it has been squeezed hard somewhere along the way. The video bitrate guide explains the numbers.
Can you tell if a video was upscaled?
Not with certainty from the metadata. An upscaled file is genuinely 3840 × 2160, so its size reads as 4K. There are hints, though:
- A bitrate far below what the resolution would normally need, visible in the Video section’s bitrate graph.
- An encoder or software tag from an editing or conversion tool rather than a camera, listed under Device and Provenance.
- Frames that look soft at full size. Frames lets you Save frame as a PNG to inspect pixel by pixel, if your browser can decode the codec.
- Camera details that don’t fit: a camera model that can’t record 4K, or none at all.
None of these proves upscaling on its own. They are reasons to look closer, not a verdict. For other signs a file has been re-saved, see video forensics.
Other ways to check video resolution
- Windows: right-click the file in File Explorer, choose Properties, open the Details tab and read Frame width and Frame height. These fields are sometimes blank for MKV files.
- Mac: open the file in QuickTime Player and choose Window > Show Movie Inspector (Command-I) to see its size and aspect ratio.
- VLC: Tools > Codec Information (Ctrl+J) shows the video resolution and the buffer (coded) dimensions.
- Command line: ffprobe prints both coded and displayed sizes. More in the ffprobe guide.
ffprobe -v error -select_streams v:0 -show_entries stream=width,height,coded_width,coded_height,sample_aspect_ratio,display_aspect_ratio -of default=nw=1 file.mp4
For the frame rate that goes with the size (such as 4K at 60 fps), use the frame rate checker; for a full report of every stream, video file info.
Video resolution: common questions
Why does my 4K video look blurry after uploading it?
Platforms re-encode uploads, and players often start at a lower quality and switch up only when the connection allows. Some platforms also take longer to prepare the high-resolution versions. Check the quality setting in the player before assuming the file was the problem.
What is the difference between 4K UHD and DCI 4K?
4K UHD is 3840 × 2160 (16:9) and is used by TVs, phones and streaming. DCI 4K is 4096 × 2160, a slightly wider shape used in cinema. Both are called 4K.
Why does a tool say my 1080p video is 1920 × 1088?
That is the coded size. H.264 compresses in 16-pixel blocks, so 1080 lines are stored as 1088 and the extra 8 are cropped when the video plays. The picture you see is 1920 × 1080.
Why does my phone video show as 1920 × 1080 when it plays in portrait?
The pixels were stored in landscape and a rotation flag tells players to turn them. The checker shows both the stored size and the flag.
Is higher resolution always better quality?
No. Quality also depends on bitrate, codec, lighting, focus and how many times the file has been re-encoded. A clean 1080p file can look better than a heavily compressed 4K one.
Does the checker upload my video?
No. The file is read in your browser on your device and nothing is sent anywhere.