Demand Gen copy limits: 40-character headlines, one at 30 or fewer

Demand Gen allows headlines up to 40 characters, with at least one of them 30 characters or fewer, descriptions up to 90 characters, a business name up to 25 and videos of 10 to 60 seconds. The 30-character rule for one headline is the easy one to miss, so check for it explicitly.

The copy and video limits

The Google Ads Help page on Demand Gen ad copy specs lists these values, read on 2026-10-03.

A checker that includes the 30-character rule

A plain length check misses the rule that one headline must fit in 30. This version tests it explicitly, along with counts and the URL limit.

def check_demand_gen(ad):
    problems = []
    heads = ad["headlines"]
    if not 1 <= len(heads) <= 5:
        problems.append("headlines: need 1-5")
    for h in heads:
        if len(h) > 40:
            problems.append(f"headline over 40 ({len(h)}): {h!r}")
    if heads and min(len(h) for h in heads) > 30:
        problems.append("no headline is 30 characters or fewer")
    descs = ad["descriptions"]
    if not 1 <= len(descs) <= 5:
        problems.append("descriptions: need 1-5")
    for d in descs:
        if len(d) > 90:
            problems.append(f"description over 90 ({len(d)}): {d!r}")
    if len(ad["business_name"]) > 25:
        problems.append("business name over 25")
    if len(ad["final_url"]) > 2048:
        problems.append("final URL over 2048")
    return problems

ad = {
    "headlines": ["Trail shoes built for wet ground", "Lightweight and grippy"],
    "descriptions": ["Try them for 30 days with free returns."],
    "business_name": "Northline Outfitters",
    "final_url": "https://example.com/trail-shoes",
}
print(check_demand_gen(ad) or "ok")

Reaching 10 to 60 seconds with Sume video

The video docs say most catalog models top out at 15 seconds, while seedance-2.5 accepts 4 to 30 seconds and wan-3.0 accepts 2 to 30 seconds. A 10-second video is within reach of any model whose supported_durations includes 10, but 30 to 60 seconds takes either a long-range model or an assembly.

Timeline 1.0 assembles ordered clips with an audio spine up to 1,800 seconds, so a 45-second cut can be built from several generated shots plus a voiceover. Timeline's default output is 1080x1920, so set output.width and output.height for landscape or square placements.

Order of work

Fix the copy first, since it sets the message. Then render video to the length the placement needs and run the checker on the final strings. Keep the 30-character headline as a real, standalone claim, not a truncated version of a longer line.