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Check before you hand off

Video spec checker for short-form uploads

Video spec checker results compare a finished video's duration, file size, dimensions, and format with the core limits Postdom has validated for TikTok, Instagram Reels, YouTube Shorts, LinkedIn, Facebook Reels, X, Snapchat Spotlight, Threads, and Bluesky. A check reads Unknown where a destination publishes no enforced bound. Enter values manually or read browser-visible local metadata; nothing is uploaded.

Useful for: a finished short-form video whose exported details you can inspect.

Not included: trimming, resizing, generating, uploading, publishing, or predicting destination acceptance.

Use the checker

How does this video spec checker work?

Choose a destination, then enter the values shown by your editor or exported file. An optional local-file reader can fill browser-visible metadata. Review the fields before running the result.

Optional: choose a local video to read the exact file size, browser-reported MIME type, dimensions, and raw duration. The reported type may be empty or inaccurate. Nothing is uploaded.

Ready when you are

Enter the exported video's details, then run the check.

Missing input stays missing. The checker never treats a blank field as zero or a not-published rule as a pass.

A useful order

What should I fix first?

Correct hard failures before revisiting recommendations. Do not “fix” an Unknown result by inventing a number.

  1. 1

    Confirm the exported file

    Use the final export, not the editor timeline. File properties and export details are the source for the manual fields.

  2. 2

    Repair a failed rule

    Re-export only what the result identifies: format, file size, duration, dimensions, or frame shape. Renaming a file does not change its format.

  3. 3

    Keep Unknown visible

    A not-published minimum or ratio is not evidence that zero or every value is allowed. Check the selected account and destination before handoff.

  4. 4

    Review the finished video

    Passing local specs cannot approve the content, audience, consent, disclosure, account, or destination policy. A human still owns those decisions.

The rules behind the result

Which limits are checked for each destination?

Every row below is rendered from @postdom/core. An enforced rule can fail a preflight. A recommendation cannot. Not published stays visible and never becomes zero.

Destination

TikTok

7 enforced rules · 2 recommendations · 2 not-published fields

RuleValueStatus and source
Minimum durationNot publishedNot publishedOfficial source · verified
Maximum duration10 minutes (600 seconds)EnforcedOfficial source · verified
Accepted upload formatsMP4 or QuickTimeEnforcedOfficial source · verified
Minimum resolutionwidth: 360 · height: 360EnforcedOfficial source · verified
Maximum resolutionwidth: 4,096 · height: 4,096EnforcedOfficial source · verified
Recommended resolutionquality: 720p or higherRecommendationOfficial source · verified
Aspect ratio ruleNot publishedNot publishedOfficial source · verified
Account maximum can varyYesEnforcedOfficial source · verified
Recommended aspect ratio9:16RecommendationOfficial source · verified
Postdom file-size ceiling500 MiB (524,288,000 bytes)EnforcedPostdom core architecture record · verified
Postdom accepted upload formatsMP4 or QuickTimeEnforcedPostdom core architecture record · verified

Destination

Instagram Reels

7 enforced rules · 1 recommendations · 2 not-published fields

RuleValueStatus and source
Minimum duration3 secondsEnforcedOfficial source · verified
Maximum duration15 minutes (900 seconds)EnforcedOfficial source · verified
Accepted upload formatsMP4 or QuickTimeEnforcedOfficial source · verified
Minimum resolutionNot publishedNot publishedOfficial source · verified
Maximum horizontal resolution1,920EnforcedOfficial source · verified
Recommended resolutionNot publishedNot publishedOfficial source · verified
Aspect ratio ruleminimum: 0.01 · maximum: 10EnforcedOfficial source · verified
Recommended aspect ratio9:16RecommendationOfficial source · verified
Postdom file-size ceiling500 MiB (524,288,000 bytes)EnforcedPostdom core architecture record · verified
Postdom accepted upload formatsMP4 or QuickTimeEnforcedPostdom core architecture record · verified

Destination

YouTube Shorts

6 enforced rules · 0 recommendations · 4 not-published fields

RuleValueStatus and source
Minimum durationNot publishedNot publishedOfficial source · verified
Maximum duration3 minutes (180 seconds)EnforcedOfficial source · verified
Accepted upload formatsMP4 or QuickTimeEnforcedOfficial source · verified
Minimum resolutionNot publishedNot publishedOfficial source · verified
Recommended resolutionNot publishedNot publishedOfficial source · verified
Aspect ratio rulemaximum width to height ratio: 1EnforcedOfficial source · verified
Recommended aspect ratioNot publishedNot publishedOfficial source · verified
Shorts qualificationorientation: square or vertical · maximum duration seconds: 180 · applies to uploads on or after: 2024-10-15EnforcedOfficial source · verified
Postdom file-size ceiling500 MiB (524,288,000 bytes)EnforcedPostdom core architecture record · verified
Postdom accepted upload formatsMP4 or QuickTimeEnforcedPostdom core architecture record · verified

Destination

LinkedIn

3 enforced rules · 4 recommendations · 1 not-published fields

RuleValueStatus and source
Destination file-size ceiling5 GiB (5,368,709,120 bytes)RecommendationOfficial source · verified
Accepted upload formatsMP4EnforcedOfficial source · verified
Maximum durationNot publishedNot publishedOfficial source · verified
Minimum resolutionlongest side: 256 · shortest side: 144RecommendationOfficial source · verified
Maximum resolutionlongest side: 4,096 · shortest side: 2,304RecommendationOfficial source · verified
Aspect ratio ruleminimum: 0.416667 · maximum: 2.4RecommendationOfficial source · verified
Postdom file-size ceiling500 MiB (524,288,000 bytes)EnforcedPostdom core architecture record · verified
Postdom accepted upload formatsMP4 or QuickTimeEnforcedPostdom core architecture record · verified

Destination

Facebook Reels

4 enforced rules · 3 recommendations · 1 not-published fields

RuleValueStatus and source
Minimum duration3 secondsEnforcedOfficial source · verified
Maximum duration90 secondsEnforcedOfficial source · verified
Accepted upload formatsMP4RecommendationOfficial source · verified
Maximum resolutionNot publishedNot publishedOfficial source · verified
Recommended resolutionwidth: 1,080 · height: 1,920RecommendationOfficial source · verified
Recommended aspect ratio9:16RecommendationOfficial source · verified
Postdom file-size ceiling500 MiB (524,288,000 bytes)EnforcedPostdom core architecture record · verified
Postdom accepted upload formatsMP4 or QuickTimeEnforcedPostdom core architecture record · verified

Destination

X

4 enforced rules · 2 recommendations · 1 not-published fields

RuleValueStatus and source
Maximum duration20 minutes (1,200 seconds)EnforcedOfficial source · verified
Accepted upload formatsNot publishedNot publishedOfficial source · verified
Minimum resolutionwidth: 32 · height: 32EnforcedOfficial source · verified
Recommended resolutionwidth: 1,280 · height: 720RecommendationOfficial source · verified
Recommended aspect ratio16:9 or 1:1RecommendationOfficial source · verified
Postdom file-size ceiling500 MiB (524,288,000 bytes)EnforcedPostdom core architecture record · verified
Postdom accepted upload formatsMP4 or QuickTimeEnforcedPostdom core architecture record · verified

Destination

Snapchat Spotlight

6 enforced rules · 0 recommendations · 2 not-published fields

RuleValueStatus and source
Minimum duration6 secondsEnforcedOfficial source · verified
Maximum duration1 minutes (60 seconds)EnforcedOfficial source · verified
Accepted upload formatsMP4EnforcedOfficial source · verified
Minimum resolutionwidth: 540 · height: 960EnforcedOfficial source · verified
Aspect ratio ruleNot publishedNot publishedOfficial source · verified
Maximum resolutionNot publishedNot publishedOfficial source · verified
Postdom file-size ceiling500 MiB (524,288,000 bytes)EnforcedPostdom core architecture record · verified
Postdom accepted upload formatsMP4 or QuickTimeEnforcedPostdom core architecture record · verified

Destination

Threads

6 enforced rules · 0 recommendations · 1 not-published fields

RuleValueStatus and source
Maximum duration5 minutes (300 seconds)EnforcedOfficial source · verified
Aspect ratio ruleminimum: 0.01 · maximum: 10EnforcedOfficial source · verified
Maximum horizontal resolution1,920EnforcedOfficial source · verified
Accepted upload formatsMP4 or QuickTimeEnforcedOfficial source · verified
Minimum resolutionNot publishedNot publishedOfficial source · verified
Postdom file-size ceiling500 MiB (524,288,000 bytes)EnforcedPostdom core architecture record · verified
Postdom accepted upload formatsMP4 or QuickTimeEnforcedPostdom core architecture record · verified

Destination

Bluesky

4 enforced rules · 0 recommendations · 2 not-published fields

RuleValueStatus and source
Destination file-size ceiling47.68 MiB (50,000,000 bytes)EnforcedEvidence or verification record unavailable.
Accepted upload formatsMP4EnforcedOfficial source · verified
Maximum durationNot publishedNot publishedOfficial source · verified
Aspect ratio ruleNot publishedNot publishedOfficial source · verified
Postdom file-size ceiling500 MiB (524,288,000 bytes)EnforcedPostdom core architecture record · verified
Postdom accepted upload formatsMP4 or QuickTimeEnforcedPostdom core architecture record · verified

What the shared checks do—and do not—mean

Format and file-size checks are Postdom declared-field rules shared across supported destinations. The file-size ceiling is not a provider-wide rule. Platform rows add their evidence-backed duration, dimension, and shape checks. Recommendations remain guidance and never create a rejection.

Before you rely on a result

Questions about video checks

Use the result to improve a finished file before handoff—not to replace account, content, consent, audience, disclosure, or policy review.

Does passing the checker guarantee my video will publish?

No. A pass means the entered values did not fail Postdom's local preflight rules. A destination can still reject a video because of account eligibility, permissions, content, policy, consent, audience settings, or checks that happen after handoff.

Does this page upload my video?

No. You can enter the duration, file size, width, height, and format manually. The optional local reader can use browser-visible file size, reported MIME type, and video metadata, but it does not read hidden fields, store media, or send anything to a destination.

Why can a result be Unknown?

Unknown means Postdom does not have a published or verified rule for part of that check. Unknown is not Pass, Fail, or zero. The checker preserves that gap instead of guessing a value.

Which destinations does the checker support?

Every destination has a tab: TikTok, Instagram Reels, YouTube Shorts, LinkedIn, Facebook Reels, X, Snapchat Spotlight, Threads, and Bluesky. What each tab can decide depends on what Postdom has validated for it, and that differs by destination - a row reads Unknown when no enforced bound is published, rather than guessing a pass. Postdom validates and publishes supplied finished video; it does not generate video.

After the local check

Hand off the supplied finished video carefully

Postdom publishes supplied finished video to TikTok, Instagram Reels, YouTube Shorts, LinkedIn, Facebook Reels, X, Snapchat Spotlight, Threads, and Bluesky, and checks it against whatever limits it has validated for the chosen destination. It does not generate, trim, resize, or repair the video. An accepted or scheduled request is not evidence of provider publication; read the terminal result for every destination.