Short-form vertical editing: Calculation when moving a 16:9 broadcast screen to 9:16
If you put a 1920 x 1080 broadcast screen into a 1080 x 1920 vertical frame, only 31.6% will remain, whichever you choose. Calculation of the crop window coordinates to the face position, screen budget dividing 1920px vertically into hook subtitles, game, cam, and dialogue subtitles, safe area to cover the UI, and export resolution and length baseline were all organized into numbers.
ClipSpray Team
ClipSprayKey takeaways
- When putting 1920 No matter which one you choose, the share you throw away is the same, but what you throw away is different.
- The size of the crop window is fixed at 608 x 1080, and there is only one horizontal starting point to determine. For center alignment, x0 is 656, and to follow the face, subtract 304 from the point of interest.
- Vertical 1920px is divided by budget, not ratio. If you divide it by hook subtitles 320, game 608, cam 608, and dialogue subtitles 384, it becomes exactly 1920px.
- The entire screen is not visible. Since the UI covers the top, bottom, and right sides, the actual safe area is about 918 x 1306, which is about 58% of the frame width.
- The maximum resolution that can be uploaded as shorts is 1080p. There is no benefit to exporting in 4K, and the upper limit and recommended vertical frame is 1080 x 1920.
The reason vertical editing is difficult is not because of a lack of sense. This is because the moment you put a horizontal picture into a vertical frame, it becomes an arithmetic problem of having to choose what to discard. This article calculates how many pixels are actually left when moving a 1920 x 1080 broadcast screen to a 1080 x 1920 shorts frame, and where those pixels should be distributed.
What remains if you move the 16:9 broadcast screen to 9:16?
No matter which method you choose, only 31.6% remains. Cropping leaves 31.6% of the picture, and letterboxing only fills 31.6% of the screen.
Put 16:9 original into 9:16 frame (1920 x 1080 → 1080 x 1920)
Method 1. Fill (crop)
Vertical alignment scale s = 1920 / 1080 = 1.778
Original width remaining on screen = 1080 / 1.778 = 607.5px
Original retention rate = 607.5 / 1920 = 31.6%
Discarded width = 1312.5px (656px left and right)
Method 2. Insert as a whole (letterbox)
Horizontal scale s = 1080 / 1920 = 0.5625
Height occupied by image = 1080 x 0.5625 = 607.5px
Screen occupancy = 607.5 / 1920 = 31.6%
Remaining margin = 1312.5px (656px each at top and bottom)
It is no coincidence that the two values are the same. 16:9 and 9:16 are reversed ratios, so putting one into the other gives you the square of (9/16), or 0.316. So the choice is not how much to lose, but what to lose.
Where should I place the crop window?
The size is already determined. It's 608 x 1080, and there's only one horizontal starting point to decide.
Crop window size = 608 x 1080 (based on original coordinate system, fixed)
When centered
x0 = (1920 - 608) / 2 = 656
To center the point of interest cx
x0 = cx - 304
However, it is cut to fit between 0 and 1312.
Example) If the cam is near x = 1700 at the bottom right
x0 = 1700 - 304 = 1396 → set to upper limit of 1312
Result: 608px section attached to the right end of the original
What's important on a broadcast screen is usually not in the center. The cam is usually located in the bottom right, with game information on the left and right edges. If you leave center alignment as the default, everything you really need to see is cut out.
So in real work, we have to re-capture x0 for each clip. Even within one clip, if there is a section where cam reaction is important and a section where the game screen is important, it is better to move x0 at that point. Which sections in game broadcasts are such are covered in How to edit game broadcasts].
How can I divide the height of 1920px?
If you look at it as a question of distributing pixels rather than a question of choosing a ratio, the answer will come out quickly.
There is one key. If you fit a 16:9 screen to 1080px width, the height is automatically set to 608px. Once this number is fixed, the rest is subtraction.
When adjusting a 16:9 screen to 1080px horizontally
Height = 1080 x 9 / 16 = 607.5 ≈ 608px
Vertical budget (total 1920px)
Top hook subtitle 320px
Game screen 16:9 608px
Cam screen 16:9 608px
Bottom dialogue subtitle 384px
----------------------
Total 1920px
This distribution is not an absolute standard. If it's a clip that only uses a game without a cam, the game screen will be enlarged, and if it's a broadcast that's all about the cam, like Jeochat, the cam will be enlarged. However, if you calculate the sum of any combination to be 1920, you will avoid accidents where the subtitles are pushed off the screen later.
Where should the subtitles be placed?
The entire vertical screen is not visible. Only the inside that is left aside by the UI is the area that is actually read.
YouTube does not disclose the pixel number of safe areas in official documents. However, you can immediately check what is on the screen by opening it with your phone. Search and notifications are placed vertically at the top, channel name, description, and sound information at the bottom, and reaction buttons are placed vertically on the right.
Below are the margin values used in this article based on that observation. Please read these as a working baseline, not official figures.
| direction | Width left blank | Based on 1080 x 1920 | What goes on |
|---|---|---|---|
| top | About 12% | 230px | Search, notification icon |
| Bottom | About 20% | 384px | Channel name, description, sound, tab |
| Right | About 15% | 162px | Like, Comment, Share, Remix |
| Remaining safe area | 918 x 1306 | Approximately 58% of frame width |
There are three practical rules that emerge from this table: Dialogue subtitles are placed about one-third of the way up from the bottom rather than at the bottom of the screen, hook subtitles are placed 12% below the top to avoid the top icon, and faces are placed in a place that does not overlap with the reaction button row on the right. How to cut and trim the subtitles themselves is organized separately in Automatically Generate Short Subtitles.
What should be the export resolution?
1080 x 1920 is sufficient. There is no benefit beyond that.
YouTube Getting Started with Shorts document states that "The maximum resolution that can be uploaded for Shorts videos is 1080p". Even if the original is recorded in 1440p or 4K, the upper limit for files uploaded as shorts is 1080p.
There is a common mistake here. Because the original image quality is good, I think it is okay to crop it. If you calculate it, it is different.
When the original is 1920 x 1080
Crop section increased from 608 x 1080 to 1080 x 1920
→ Magnification factor: 1.778x, section filled with pixels
When the original is 2560 x 1440
Crop section increased from 810 x 1440 to 1080 x 1920
→ Magnification magnification 1.333x, with room to spare
When the original is 3840 x 2160
Reduce crop section 1215 x 2160 to 1080 x 1920
→ Zoom out, no loss of image quality
If broadcasting with the assumption of vertical editing, the cheapest way to improve picture quality is to raise the recording resolution to 1440p or higher. Uploads are lowered to 1080p, but the amount of original information in the cropped section varies. How to set recording settings in OBS is summarized in OBS Setting Method.
If you are thinking of using vertical videos in long form, there is one more thing to check. When playing the 9:16 vertical video on your computer's browser, YouTube advises "You may want to add padding for an optimal viewing experience". For long form, it is better to use the original 16:9 format.
How long should I cut it to?
There are three official baselines, of which 60 seconds is the most important.
| baseline | Evidence | practical meaning |
|---|---|---|
| 180 seconds | If they are square or have a vertical ratio of less than 3 minutes, they are classified as shorts | Ceiling, not goal |
| 90 seconds | Audio Library Most Songs Usage Limit | If you plan to write music, stop here |
| 60 seconds | Block globally if longer than 1 minute and active copyright report | Effective upper limit for clips containing sound sources |
| 30 seconds | Restrictions on the use of some tracks | May be shorter depending on the song |
To summarize, it is like this. The section containing the sound source ends within 60 seconds, and only the broadcast original sound is left for clips longer than 60 seconds. The length and beat are not issues that are determined separately, but are decided together, and the reason for this is discussed in detail in Broadcast clips edited with AI, the selection that is involved in the monetization review.
What is the actual work order?
Calculation comes first, editing comes next. If you do the opposite, the subtitles will be cut off after you've finished creating them, so you'll have to start over from the beginning.
1️⃣ Confirm section and length: Decide the section to be written and first decide whether it is inside or outside 60 seconds depending on whether or not the sound source is included. This decision changes all subsequent arrangements.
2️⃣ Choose placement: Choose one of three options: only the game, split the game and cam up and down, or use only the cam in large format. It is more stable if you do not change the arrangement in the middle of the clip.
3️⃣ Calculate your vertical budget: Divide 1920px into even placement. The 16:9 area is fixed at 608px based on 1080px width, and the remaining pixels become the subtitles.
4️⃣ Get crop window coordinates: Determine x0 of the original section to enter each area. Center 656 is the default, move it to the side where the cam or important information is located.
5️⃣ Place subtitles within safe area: Make sure the subtitles and face fit inside the 918 x 1306 area. If you reduce it to the size of your phone screen, you will immediately be able to see if it is readable.
6️⃣ Export as 1080 x 1920: The upper limit is 1080p, so anything beyond that is unnecessary. After exporting, play it once on your phone and check whether the subtitles are displayed in the bottom UI.
In long replays, repeating this process clip by clip is the real bottleneck. ClipSpray receives the entire replay of Czyzyk and SOOP, selects candidate sections, and exports a 9:16 vertical edit and a 16:9 horizontal clip with subtitles and titles.
Frequently Asked Questions
Why is it awkward if the broadcast screen is cut straight to 9:16?
This is because only 608px of the original width of 1920px remains. The ratio is 31.6%, and the remaining 1312px goes off the screen. Game screens often have information spread out to the left and right, so leaving only the center makes it difficult to understand the situation.
Can't I just put it all in a letterbox?
It works. However, the height of the video is 608px out of 1920px vertical, so only 31.6% of the screen is filled. The top and bottom 1312px are empty, so the video looks small on the phone, and if you don't fill that space with subtitles or cam, you'll lose a lot.
What pixels should the shorts be exported at?
1080 x 1920 is sufficient. YouTube informs you that the maximum resolution that can be uploaded as shorts is 1080p. Even if you export it larger than that, it will go down during the upload process and the file will only become heavier.
Can't the subtitles be placed at the bottom of the screen?
There is a high risk of covering it. The channel name, description, and sound information are placed at the bottom of the vertical screen, and reaction buttons are placed vertically on the right. It is safe to place dialogue subtitles about one-third of the way up from the bottom of the screen, not at the bottom.
Wouldn't splitting the cam and game up and down make the game too small?
The height of a 16:9 game screen that is 1080px wide is 608px. Although it looks small because it is about a third of the vertical frame, it is often more advantageous in conveying the situation than a crop that leaves only 31.6% of the original. You can also crop the game screen again to enlarge only the area you need.
Can I use a vertically edited clip as a YouTube long form?
Not recommended. YouTube's standard aspect ratio is 16:9, and you can add padding for an optimal viewing experience when playing 9:16 portrait videos in your computer browser. For long form, it is better to use the original 16:9 format.
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