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Veo 3.1 Fast vs Veo 3.1

vs

Which one, when

Same generation and the same spec sheet - 720p/1080p, 4/6/8 s at 24 fps, up to two guide images, native audio - so the split is purely the rate: the fast variant bills $0.15 per output second with audio and $0.1 silent, against $0.4 and $0.2, roughly 2.7x and 2x cheaper. Both expose the silent rate, which is the cheaper path when you intend to score the clip yourself. At this spec parity the fast variant is the default.

Benchmarks

Veo 3.1 Fast: the vendor has not published benchmark scores.

Veo 3.1: 12 published, but no benchmark it shares with enough other models to compare.

Veo 3.1 Fast Veo 3.1 other models measured peer average ★ no peer scored higher
SeedVideoBench 2.0 Text-to-Video (1-5) Motion · 2.39-2.73
N/A
2.73

Vendor-published: ByteDance

Pricing

Veo 3.1 Fast Veo 3.1 Δ
Per output second (with audio) $0.15 $0.4 0.37×
Per output second (silent) $0.1 $0.2 0.5×

Rates from the live catalogue at build time; each model page carries the current rate card.

Where they sit · price per output second across all 7 video-generation models on this billing unit (log scale)

Veo 3.1 Fast · $0.15 Veo 3.1 · $0.4
$0.1 · Sora 2 $0.75 · Veo 3

Capabilities

Veo 3.1 Fast Veo 3.1
Native audio yes yes

Specs

Veo 3.1 Fast Veo 3.1
Input modalities text image text image
Output modalities video video
Released 2025-10 2025-10
Resolution 720p / 1080p (fixed set) 720p / 1080p (fixed set)
Clip length 4 / 6 / 8 s (fixed set) 4 / 6 / 8 s (fixed set)
Frame rate 24 fps 24 fps
Aspect ratios
  • 16:9
  • 9:16
  • 16:9
  • 9:16
Input modes
  • text-to-video
  • first-frame & first/last-frame image-to-video (up to 2 guide images)
  • text-to-video
  • first-frame & first/last-frame image-to-video (up to 2 guide images)
Format .mp4 .mp4

Specs are transcribed from each vendor’s documentation; a row a vendor does not publish is left out rather than inferred. Full sources: Veo 3.1 Fast · Veo 3.1

One prompt, both models, measured through the gateway

PROMPT A paper boat drifts across a rain puddle at dusk. The camera pushes in slowly as a single drop lands beside it and rings spread outward across the reflection.

Veo 3.1 Fast

Model returned 1280×720 Length 8s latency 63 s

Veo 3.1

Model returned 1280×720 Length 8s latency 63 s

One prompt, one request per model, no retries and no cherry-picking. This is the first result each model returned. Neither size nor duration was pinned: each model used its own default, because a request shaped to fit all of them would flatter none. Files here are re-encoded for the web, so judge composition and prompt adherence, not compression.

Switch between them with one line

Both ids are in every tab below; the highlighted pair of lines is the only edit. Same endpoint, same key, same request shape.

import time

import requests

BASE = "https://synthorai.io/v1"
HEADERS = {"Authorization": "Bearer sk-syn-..."}

# 1) create the video generation job (POST /v1/videos)
task = requests.post(
    f"{BASE}/videos",
    headers=HEADERS,
    json={
        "model": "veo-3.1-fast-generate-001",
        # "model": "veo-3.1-generate-001",  # uncomment this line, comment the one above
        "prompt": "a watercolor lighthouse at dawn, waves rolling in, camera pulling back",
        "resolution": "720p",
        "duration": 5,
    },
).json()

# 2) poll the job until it reaches a terminal state
while task["status"] in ("queued", "in_progress"):
    time.sleep(5)
    task = requests.get(f"{BASE}/videos/{task['id']}", headers=HEADERS).json()

# 3) completed → signed video URL (valid ~24h - download and store it promptly)
if task["status"] == "completed":
    print(task["data"][0]["url"])
else:
    print(task["error"])

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FAQ

Which is cheaper, Veo 3.1 Fast or Veo 3.1?

Veo 3.1 Fast is cheaper on the "Per output second (with audio)" row ($0.15 vs $0.4, 2.7× apart). Other rows may point the other way; the table above carries the full rate card, and real cost depends on your mix.

Can I A/B test Veo 3.1 Fast against Veo 3.1 without two integrations?

Yes. Both are served through the same OpenAI-compatible endpoint with one API key. Switching is a one-line change to the model id, so you can route a fraction of traffic to each and compare bills directly.

What clip lengths and resolutions do they support?

The spec table above lists each model’s published resolutions and clip lengths, and marks whether a value is a fixed set of options or a continuous range. The two look alike but are priced differently, since per-second billing multiplies with length.

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