YouTube ad length by format, and what each costs to render in Timeline

Google's help page lists these lengths: skippable in-stream has no maximum length (under 3 minutes is recommended), non-skippable in-stream is 15 to 60 seconds depending on the campaign subtype, bumper ads are 6 seconds with a 5-second minimum, YouTube Shorts ads are under 60 seconds recommended, and Masthead ads have no maximum with more than 10 seconds recommended. On Sume Timeline, every one of those lengths up to 60 seconds bills one minute at $0.10, and a 3-minute skippable ad bills three minutes at $0.30.

The reason is how Timeline bills: the public rate is $0.10 per ceil output minute, and the reserve is ceil(audio.duration_seconds / 60) minutes. Length only changes the price when it crosses a minute boundary.

Google's length rules

The page is Google Ads Help, "YouTube video ad lengths and formats". Its entries, quoted from the format list, are: skippable in-stream "No max length ( <3 min recommended)"; non-skippable in-stream "15-60 seconds (depending on the campaign subtype)"; bumper "6 seconds (>=5 seconds minimum)"; YouTube Shorts ads "<60 seconds recommended"; Masthead "No max length (Recommend greater than 10 seconds)".

The Shorts ads page adds one more length fact: a Shorts video ad can be up to 3 minutes long, but only the first 60 seconds play on the Shorts feed. That is a different statement from the length list, so read both before trimming.

The 181-second trap

Because billing rounds up, an ad that runs one second over a minute boundary costs a whole extra minute. A 180-second skippable ad is three minutes. A 181-second one is four. For a 60-second non-skippable ad, 60 seconds is one minute and 61 seconds is two minutes.

The free plan call tells you before you spend: POST /v1/timeline-1.0/plan returns billable_minutes and estimated_cost_usd_micros without creating a job, reserving credits or downloading media. Note the docs warn that a plan cannot predict short-source pad or loop warnings.

A plan call for a bumper

Here is a plan call for a 6-second bumper. The spine can be silence while you check structure, with audio.mode set to silence, and in that mode you must not send url, parts, gain_db or source_in.

Swap duration_seconds and the slot duration to test other lengths. The plan returns duration_seconds, segment_count and billable_minutes for each.

curl -X POST https://api.sume.com/v1/timeline-1.0/plan \
  -H "Authorization: Bearer $SUME_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "audio": { "mode": "silence", "duration_seconds": 6 },
    "video": [
      {
        "source_url": "https://media.sume.com/artifacts/artf_demo/hero.mp4",
        "start": 0,
        "duration": 6
      }
    ]
  }'

Ceilings that matter

Timeline accepts audio.duration_seconds from 1 to 1800, so the longest single render is 30 minutes and would bill three dollars. That is far above the 3-minute recommendation for skippable in-stream, which is advice and not a cap. For ads, the binding number is the format's length rule on Google's page, not the Timeline ceiling.

Remember that the first 60 seconds are what plays in the Shorts feed for a Shorts ad. If you render a 3-minute file for a Shorts campaign, you pay for three Timeline minutes and 120 of those seconds are not shown in the feed per Google's page. Trim to 60 seconds and pay for one.

Matching length to the creative job

Google's length list is a limit, not an instruction on how long a good ad should be. The Shorts ads page recommends adding videos under 60 seconds to match how people watch Shorts, and says action-oriented ads should use 10 to 30 second vertical videos. A bumper is the shortest format at 6 seconds, with a 5-second minimum, which leaves room for exactly one idea.

On the Sume side, the length you pick decides the number of voiceover seconds you must produce, because the Timeline spine sets the output length: coverage by video slots can stop at most 0.5 seconds before the end of the spine. For a 6-second bumper, plan a 6-second spine and slots that sum to 5.5 seconds or more. Slots that run longer than the spine are not extended; the output length is the spine's duration_seconds.

One last cost note: the Timeline numbers in the table cover the assembly job only. If you generate the clips and the voiceover with Sume models, those are separate lines priced by model, and the catalog is the source of truth for them.