If a custom-size Loom came out softer than you expected, the size of the box you drew is the first thing to check. Loom publishes a floor for custom-size recording — 251 x 251 pixels — and says on the same page that a small capture area can pull your recording resolution down with it.
This is not a bug, and it is not your webcam. It is documented behaviour that almost nobody quotes.
What this actually means
Loom's "Record a custom-size video" page says it in two sentences:
"The minimum size for a custom size video is 251 x 251 pixels. Keep in mind that using a smaller custom size can affect the resolution of your video"
"For example, if your selected area is too small to support 4K, the system may automatically downgrade the recording resolution. To maintain higher resolutions, be sure your custom recording area is large enough."
Three things are worth pulling out of that.
251 x 251 is a floor, not a recommendation. It is the smallest custom size the page names. Recording at or near it is exactly the situation the next sentence warns about.
The downgrade is automatic and one-directional. Loom's wording is "the system may automatically downgrade" — it happens on Loom's side, at capture time, without an error message. Nothing in that sentence promises it will happen every time either; "may" is Loom's word, not a hedge we added.
The example Loom picks is 4K. The logic it describes is about the selected area being "too small to support" a resolution. So the higher the resolution you were aiming for, the larger the box has to be before that resolution is even on the table.
Why one small box degrades the video for every viewer
The downgrade does not stop at the recording. Loom's encoding page describes how it builds the playback versions: Loom "encodes the video and makes it available in all resolutions starting with the originally recorded resolution, down to 480p."
That ladder starts at whatever resolution was actually recorded. If the capture area forced a downgrade, the top rung is lower for everyone, permanently. Loom's viewer-side page confirms the same direction of travel: auto-quality "will calculate the highest possible resolution for each viewer based on internet connection and what resolution the creator of the video recorded in."
Your viewer's bandwidth can only pick from what you handed Loom.
The fastest fix
Loom's own instruction is the whole fix: "be sure your custom recording area is large enough." Draw a bigger box, or record the full screen instead of a region.
Two checks before you re-record, because a bigger box alone will not get you to 4K:
- You need the desktop app. Loom's recording-quality FAQ states that 4K requires it: "If you're on the Loom Education, Business, Business + AI or Enterprise plan and you have a 4K compatible device, you will be able to record videos in 4K (3840x 2160 pixels or larger) using the Loom desktop app on Mac and Windows."
- Your device has to clear the bar. Loom warns that "you may see a "not supported by your device" alerting you that that high resolutions are disabled in your desktop quality selector. This will happen if your device's height or camera height does not support recording in those high resolutions."
If you already have the recording and only need to move the file somewhere else, re-encoding it cannot add back pixels that were never captured — but it can bring the file size down for sharing without a second upload to anyone's server.
Try it right here
Runs in your browser. Your file is not uploaded anywhere.
This runs inside your browser tab: the file is read from disk, re-encoded locally, and handed back. Useful for the downloaded MP4 you want to attach somewhere; useless as a way to undo a resolution downgrade. Re-record if the pixels matter.
Other causes, in order of likelihood
You recorded with the Chrome extension. The extension is capped well below the desktop app regardless of how big your box is. Loom's extension settings page: "At this time, the highest video quality available on the Loom Chrome Extension is 1080p if you are on a Business, Business + AI, or Enterprise plan." Loom's plan-comparison FAQ answers the 4K question about the extension directly — "Unfortunately, no. This is a limitation of Chrome and one of the reasons we built the desktop app." The full per-recorder comparison is in Loom's extension vs desktop app quality gap.
Your plan or your role. Loom's quality page states that "Loom Starter users can choose their recording resolution up to 720p," and that paid users on Education, Business, Business + AI and Enterprise "can choose to record in various resolutions, including HD, while using the Loom desktop app." The trap is the role, not the plan: "Users on a Creator Lite role will be limited to resolutions under Loom Starter free plan." That same role restriction is behind the 5-minute cap some paid users still hit.
Custom recording size is itself listed as a paid capability — Loom's plan-differences page includes "custom recording size" in the list of what a Business plan adds.
Your monitor is large. Loom states this plainly: "If you're using a larger monitor, you will see some quality loss in your recordings. To combat this, you can change your monitor resolution to 1920x1080 to match 1080 pixels guideline." Loom does not put a number on how much quality is lost, so neither will we.
You are in Cam only mode on Windows. Loom's quality page lists the Windows desktop app as "up to 4K" with one exception in brackets: "it's not possible to record above 1080p on Cam only."
The video is stretched, not soft. That is a different problem with a different cause. Loom says "Our web player adjusts the aspect ratio of a video to 16:9 (1280 x 800), which makes the video appear proportional." But "when you download a video, it is in the original aspect ratio the video was recorded in. That being said if you recorded in an atypical aspect ratio your video may look stretched out." A hand-drawn custom box is an atypical aspect ratio by definition. Loom's suggestion is "changing your screen resolution to a 16:9 ratio."
How to tell it worked
Play the finished video and open the quality selector — the resolutions offered are the ladder Loom built from your recording, so the top entry tells you what actually got captured. One caveat from Loom: "The video quality selector is not available for video's that have been trimmed or stitched at this time." If you trimmed the test recording, you lose the fastest way to check.
The other check is the file itself. Download it and read the pixel dimensions in your file manager or player. Loom downloads are always MP4 — "All videos downloaded from Loom will be in a .MP4 format" — so any tool can read the dimensions.
FAQ
What is the minimum custom size for a Loom recording? 251 x 251 pixels. Loom's custom-size page states it directly, and pairs it with the warning that a smaller custom size "can affect the resolution of your video."
Does a custom size recording always lose quality? No. Loom's wording is that the system "may automatically downgrade the recording resolution" when the selected area is "too small to support" the resolution you wanted. A generously sized box on a capable device is not the case being described.
Can I record in 4K with a custom size area? Only if the area is large enough for it, and only on the desktop app with a paid plan and, in Loom's words, "a 4K compatible device." The Chrome extension tops out at 1080p regardless.
Can I restore the resolution after recording? Not from the recording itself — the downgrade happens at capture. Upscaling afterwards invents pixels rather than recovering them. Re-record with a larger capture area instead.
Why does my custom-size Loom look stretched only after I download it? Because the web player normalises it and the download does not. Loom describes the player as adjusting the aspect ratio "to 16:9 (1280 x 800)", while a downloaded file keeps "the original aspect ratio the video was recorded in."
Need to shrink that downloaded MP4 for email or a chat app? Compress video in your browser — nothing is uploaded. More Loom and recording fixes live in the fix guides, and the full toolbox is at all Clapr tools.
Quotes taken from Loom's help centre pages on custom-size recording, recording quality, video encoding settings, and downloads, checked 16 September 2026. Loom's pages disagree with each other in places — verify anything load-bearing against the current official documentation.
