GPT-6 Luna

GPT-6 Luna is the small, cost-efficient tier of OpenAI's GPT-6 family, sitting below GPT-6 Sol and GPT-6 Astra.

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input · usd / 1m tok

$0.10

output · usd / 1m tok

$0.50

context window

1.05mtokens

modalities · in → out

pricing

base api ratesusd per 1m tokens

input: $0.10over 272k · $0.20
output: $0.50over 272k · $0.75
cache read: $0.01over 272k · $0.02
cache write · default ttl: $0.125over 272k · $0.25

brackets are by input tokens per request: a request over a threshold is billed at that bracket's rates for all of its tokens. cache creation can have a separate charge.

providers

OpenAI hosts GPT-6 Luna. Impossibl routes your request intelligently and handles failover automatically when a provider is down.

OpenAI

specifications

takes text and image in, gives text outopenai/gpt-6-luna

creatorOpenAI
model typeText generation
context window1,050,000 tokens
maximum outputnot published
input
takes text and image in, gives text out
outputtext
tool callingnot verified
releasedsep 22, 2026
endpoint/v1/chat/completions

unknown means the public catalog does not establish that fact. a model's documented capabilities can differ from what a particular api supports. see the model documentation for integration details.

try it · your prompt, this model, live

# responses API
import os
from openai import OpenAI

client = OpenAI(
    api_key=os.environ["IMPOSSIBL_API_KEY"],
    base_url="https://api.impossibl.com/v1",
)

resp = client.responses.create(
    model="openai/gpt-6-luna",
    input="▌",
)
print(resp.output_text)

edit the prompt, then run

# responses API
import os
from openai import OpenAI

client = OpenAI(
    api_key=os.environ["IMPOSSIBL_API_KEY"],
    base_url="https://api.impossibl.com/v1",
)

resp = client.responses.create(
    model="openai/gpt-6-luna",
    input="▌",
)
print(resp.output_text)

edit the prompt, then run

benchmarks

benchmark results are not available for this model yet.

compare GPT-6 Luna with other models

frontier labs and open weights, best-ranked firstusd / 1m tok · in / out

anthropic/claude-fable-5-1$10.00 / $50.00compare →
meta/muse-spark-1.3$1.25 / $4.25compare →
zai/glm-5.3$1.40 / $4.40compare →
xai/grok-4.6$2.00 / $6.00compare →

impossibl models --all →

frequently asked questions

What is GPT-6 Luna?

GPT-6 Luna is the small, cost-efficient tier of OpenAI's GPT-6 family, sitting below GPT-6 Sol and GPT-6 Astra. It targets high-volume, latency-sensitive work such as chat, classification and lightweight agents, and at higher reasoning effort it takes on tasks that previously needed a Sol-tier model.

How much does GPT-6 Luna cost?

GPT-6 Luna costs $0.10 per million input tokens and $0.50 per million output tokens through the Impossibl API. Cache reads cost $0.01 per million tokens; cache writes cost $0.125 per million tokens. These base rates apply through 272,000 total input tokens per request. Above 272,000 input tokens, the long-context rates in the pricing table apply to the whole request. All rates are in USD.

view the pricing table ↑

What is the context length of GPT-6 Luna?

GPT-6 Luna has a 1,050,000-token context window through the Impossibl API.

What inputs and outputs does GPT-6 Luna support?

GPT-6 Luna accepts text and image as input. GPT-6 Luna returns text.

How do I use GPT-6 Luna through an API?

GPT-6 Luna is available through the Impossibl API. Use openai/gpt-6-luna as the model identifier with /v1/chat/completions. The quickstart explains how to create an API key and send your first request.

follow the api quickstart →

When was GPT-6 Luna released?

OpenAI released GPT-6 Luna on September 22, 2026.

Creator release announcement ↗

this page describes GPT-6 Luna as listed by the impossibl public api. prices and availability come from that catalog, refreshed here every five minutes. this is an impossibl offering, not a comparison of independent hosting-provider quotes. model descriptions and release dates, where available, use the creator sources linked under the answers above.

view the source catalog ↗model as markdown ↗report a correction →