Railwail
Accedi

Granite Code 8B vs GPT-6 Luna: 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.

Replicate
Code
vs
OpenAI
Text & Chat
Verdict

Choose GPT-6 Luna for long documents (1.1M tokens context). Choose Granite Code 8B for shorter prompts where the smaller window keeps latency and cost down.

These models serve different use cases (Code vs Text & Chat) — pick the one whose category matches your workload.

Side-by-side specs

SpecGranite Code 8BGPT-6 Luna
ProviderReplicateOpenAI
CategoryCodeText & Chat
Input cost / 1M tokens$0.060n/a
Output cost / 1M tokens$0.30n/a
Context window128K tokens1.1M tokens
Max output tokens8,192128,000
Avg. latency——
Featured——
New—Yes
Capabilities
text
—

Pricing example

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

Granite Code 8B
$0.021

100K in × $0.060 + 50K out × $0.30

GPT-6 Luna
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 Granite Code 8B
let r = await client.chat.completions.create({
  model: "ibm-granite/granite-8b-code-instruct-128k",
  messages: [{ role: "user", content: "Hello" }],
});

// After — switched to GPT-6 Luna
r = await client.chat.completions.create({
  model: "gpt-6-luna",
  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 Granite Code 8B
r = client.chat.completions.create(
    model="ibm-granite/granite-8b-code-instruct-128k",
    messages=[{"role": "user", "content": "Hello"}],
)

# After — switched to GPT-6 Luna
r = client.chat.completions.create(
    model="gpt-6-luna",
    messages=[{"role": "user", "content": "Hello"}],
)
cURL
# Before — using Granite Code 8B
curl https://railwail.com/v1/chat/completions \
  -H "Authorization: Bearer $RAILWAIL_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "ibm-granite/granite-8b-code-instruct-128k",
    "messages": [{"role": "user", "content": "Hello"}]
  }'

# After — switched to GPT-6 Luna
curl https://railwail.com/v1/chat/completions \
  -H "Authorization: Bearer $RAILWAIL_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "gpt-6-luna",
    "messages": [{"role": "user", "content": "Hello"}]
  }'

Which one wins for...

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

Coding
Granite Code 8B

Higher coding category match or larger context wins.

Writing
GPT-6 Luna

Bigger context window helps maintain long-form coherence.

Long documents
GPT-6 Luna

The larger context window is the deciding factor.

Vision
GPT-6 Luna

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, Granite Code 8B or GPT-6 Luna?
Granite Code 8B and GPT-6 Luna 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, Granite Code 8B or GPT-6 Luna?
GPT-6 Luna has the larger context window at 1.1M tokens, compared to 128K tokens for Granite Code 8B.
Is Granite Code 8B better than GPT-6 Luna for coding?
For coding-heavy workloads we lean toward Granite Code 8B 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 Granite Code 8B and GPT-6 Luna via Railwail?
Yes. Both Granite Code 8B and GPT-6 Luna 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 Granite Code 8B to GPT-6 Luna?
Replace the model identifier "ibm-granite/granite-8b-code-instruct-128k" with "gpt-6-luna" 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 Granite Code 8B and GPT-6 Luna side by side

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

Get Started FreeView Granite Code 8BView GPT-6 Luna