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Gemini 3.1 Pro vs SAM 2 (Segment Anything 2): Which AI Model Should You Choose?

Pricing, context windows, latency, capabilities, and a one-line code switch — everything you need to pick the right model.

Google
Multimodal
vs
Replicate
Multimodal
Verdict

Gemini 3.1 Pro and SAM 2 (Segment Anything 2) are closely matched on pricing and context. The right choice depends on your specific workload — see the table below for the full breakdown.

Side-by-side specs

SpecGemini 3.1 ProSAM 2 (Segment Anything 2)
ProviderGoogleReplicate
CategoryMultimodalMultimodal
Input cost / 1M tokens$2.40n/a
Output cost / 1M tokens$14.40n/a
Context window2.0M tokens—
Max output tokens65,536—
Avg. latency——
FeaturedYesYes
NewYes—
Capabilities
text
image
audio
video
image
video

Pricing example

A typical chat workload of 100,000 input tokens plus 50,000 output tokens.

Gemini 3.1 Pro
$0.96

100K in × $2.40 + 50K out × $14.40

SAM 2 (Segment Anything 2)
n/a

100K in × n/a + 50K out × n/a

Switch in one line

Both models live behind Railwail's OpenAI-compatible endpoint. Replace the model string and you are done.

JavaScript / TypeScript
import OpenAI from "openai";

const client = new OpenAI({
  apiKey: process.env.RAILWAIL_API_KEY,
  baseURL: "https://railwail.com/v1",
});

// Before — using Gemini 3.1 Pro
let r = await client.chat.completions.create({
  model: "gemini-3.1-pro-preview",
  messages: [{ role: "user", content: "Hello" }],
});

// After — switched to SAM 2 (Segment Anything 2)
r = await client.chat.completions.create({
  model: "meta/sam-2",
  messages: [{ role: "user", content: "Hello" }],
});
Python
from openai import OpenAI

client = OpenAI(
    api_key=os.environ["RAILWAIL_API_KEY"],
    base_url="https://railwail.com/v1",
)

# Before — using Gemini 3.1 Pro
r = client.chat.completions.create(
    model="gemini-3.1-pro-preview",
    messages=[{"role": "user", "content": "Hello"}],
)

# After — switched to SAM 2 (Segment Anything 2)
r = client.chat.completions.create(
    model="meta/sam-2",
    messages=[{"role": "user", "content": "Hello"}],
)
cURL
# Before — using Gemini 3.1 Pro
curl https://railwail.com/v1/chat/completions \
  -H "Authorization: Bearer $RAILWAIL_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "gemini-3.1-pro-preview",
    "messages": [{"role": "user", "content": "Hello"}]
  }'

# After — switched to SAM 2 (Segment Anything 2)
curl https://railwail.com/v1/chat/completions \
  -H "Authorization: Bearer $RAILWAIL_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "meta/sam-2",
    "messages": [{"role": "user", "content": "Hello"}]
  }'

Which one wins for...

Quick verdicts derived from public specs. Always validate on your own workload.

Coding
Gemini 3.1 Pro

Higher coding category match or larger context wins.

Writing
Gemini 3.1 Pro

Bigger context window helps maintain long-form coherence.

Long documents
Gemini 3.1 Pro

The larger context window is the deciding factor.

Vision
Tie

Multimodal/vision support is required for image inputs.

Real-time chat
Tie

Lower average latency wins for interactive UX.

Cost-sensitive
Tie

The model with the lower input-token price wins.

Frequently asked questions

Which is cheaper, Gemini 3.1 Pro or SAM 2 (Segment Anything 2)?
Gemini 3.1 Pro and SAM 2 (Segment Anything 2) cannot be compared on per-token price: at least one of them has no per-token price listed (it is priced per run or not yet priced). See each model page for its current price.
Which has more context, Gemini 3.1 Pro or SAM 2 (Segment Anything 2)?
Gemini 3.1 Pro has the larger context window at 2.0M tokens, compared to — for SAM 2 (Segment Anything 2).
Is Gemini 3.1 Pro better than SAM 2 (Segment Anything 2) for coding?
For coding-heavy workloads we lean toward Gemini 3.1 Pro on this comparison — it scores higher on the relevant heuristics (category, tags, or context window). Both models are usable for code via Railwail's OpenAI-compatible endpoint, so the safest path is to A/B test on your own prompts.
Can I use both Gemini 3.1 Pro and SAM 2 (Segment Anything 2) via Railwail?
Yes. Both Gemini 3.1 Pro and SAM 2 (Segment Anything 2) are accessible through a single Railwail API key and the OpenAI-compatible /v1/chat/completions endpoint. You only change the "model" parameter to switch between them — no SDK swap, no separate billing.
How do I switch from Gemini 3.1 Pro to SAM 2 (Segment Anything 2)?
Replace the model identifier "gemini-3.1-pro-preview" with "meta/sam-2" in your request payload. Everything else — API key, base URL, request shape — stays the same. See the code example on this page for the exact one-line change.

Try Gemini 3.1 Pro and SAM 2 (Segment Anything 2) side by side

One API key, one endpoint, both models. Start free — no credit card required.

Get Started FreeView Gemini 3.1 ProView SAM 2 (Segment Anything 2)