OpenAI
GPT-6 Luna
The cheapest GPT-6 at $0.10/$0.50 per million tokens — half GPT-5.6 Luna's promotional input rate and 42% of its output rate — with no measurable gain over it on independent data: Humanity's Last Exam (38.5% vs 39.5%), LiveBench (72.0 vs 73.6) and ARC-AGI-2 (59.31% vs 59.6%) all tie inside their noise bands, same evaluators and max effort. Eight of the eleven boards hadn't scored GPT-6 Luna yet.
GPT-6 Luna benchmarks and pricing, every number sourced: 4 tracked GPT-6 Luna benchmark scores (3 independently run, 1 still resting on a vendor’s own claim), priced at $0.10 per million input tokens and $0.50 per million output.
GPT-6 Luna’s 4 benchmark scores on this page were each verified against their sources between 2026-09-22 and 2026-09-23.
- Released
- 2026-09-22
- License
- proprietary
- Context window
- 1M tokens
- Knowledge cutoff
- 2026-05-18
- Parameters
- Not disclosed
- Architecture
- Not disclosed
GPT-6 Luna’s verified record
GPT-6 Luna’s most-compared rival is Claude Opus 5: 3 trails and 1 not callable across their 4 shared comparisons. GPT-6 Luna is priced at $0.10/$0.50 per 1M tokens (in/out) vs Claude Opus 5’s $5.00/$25.00.
Against the 86 head-to-head comparisons GPT-6 Luna shares with other tracked models: 48 real gaps, 12 inside the noise band, and 26 we will not call.
A gap counts for GPT-6 Luna only where both sides were run independently and the benchmark still separates models. Losses are listed alongside wins on purpose — GPT-6 Luna trails on 47 of them.
HLE · no tools Reasoning
±2 is noiseLiveBench Composite score across 7 domains
±2.7 is noiseARC-AGI-2 · max Compositional visual reasoning
±9.2 is noiseNo verdict for GPT-6 Luna anywhere on DeepSWE (nothing independently confirmed on both sides).
- None of GPT-6 Luna’s coding comparisons are independently confirmed on both sides yet.
GPT-6 Luna API pricing
$0.10 in / $0.50 out per 1M tokens — official pricing
What GPT-6 Luna costs per job
| Workload | Tokens in / out | Cost |
|---|---|---|
| One long chat turn | 100K / 10K | $0.015 |
| A codebase review | 1,000K / 100K | $0.150 |
| A day of agent work | 10,000K / 1,000K | $1.50 |
Computed from GPT-6 Luna’s list rates above — cache discounts and batch tiers are not applied.
GPT-6 Luna is one of 5 OpenAI models tracked on this site, at these official list prices.
| Model | In / 1M | Out / 1M |
|---|---|---|
| GPT-6 Luna | $0.10 | $0.50 |
| GPT-6 Sol | $2.00 | $10.00 |
| GPT-6 Astra | $10.00 | $50.00 |
| GPT-5.6 Luna | $0.20 | $1.20 |
| GPT-5.6 Sol | $4.00 | $20.00 |
GPT-6 Luna benchmark scores
| Benchmark | Score |
|---|---|
| HLE(no tools)[1] Reasoning · ±2 is noise | |
| ARC-AGI-2(max)[2] Compositional visual reasoning · ±9.2 is noise | |
| LiveBench[3] Composite score across 7 domains · ±2.7 is noise | |
| DeepSWE[4] Long-horizon coding · ±9.5 is noise |
Who ran these numbers: 3 of 4 independent — artificialanalysis.ai (1), arcprize.org (1), livebench.ai (1); vendor self-reported (1).
- HLE: AA's own run of GPT-6 Luna at max effort, text-only 2,158-question subset.
- ARC-AGI-2: ARC Prize's own leaderboard row at the max effort tier ($0.062/task); v2.json dataset generated 2026-09-22.
- LiveBench: Board row 'GPT-6 Luna Max Effort' on the 2026-06-25 LiveBench release; only tier populated for this model.
- DeepSWE: OpenAI's own launch-post figure (max effort). No independent DeepSWE run for this model has appeared on deepswe.datacurve.ai or via Artificial Analysis's own agent-harness runs yet — unlike GPT-6 Sol, which AA has run through its Codex agent.
Notes on the record
Pricing is tiered by prompt length, confirmed on developers.openai.com/api/docs/models/gpt-6-luna: $0.10 input / $0.50 output per million tokens under 272,000 prompt tokens (cached input $0.01), rising to $0.20/$0.75 (cached $0.02) — 2x input and cache, 1.5x output, billed on the full request — once a prompt crosses that threshold, per OpenAI's own wording. OpenAI's comparison table reads "$0.20→$0.10 input, $1.20→$0.50 output, 50% cheaper" against GPT-5.6 Luna, but calls that $0.20/$1.20 rate "promotional pricing" — GPT-6 Luna's own price is presented as standard, not a further discount on a discount.
Context window 1,050,000 tokens, max output 128,000. Input: text and images. Output: text only. Knowledge cutoff May 18, 2026. License not stated for GPT-6 Luna; inferred proprietary, API-only.
No OpenAI page calls this a replacement for GPT-5.6 Luna. Beyond the absence of "supersede"/"replace" language, GPT-5.6 Luna is explicitly still in active use elsewhere on OpenAI's own site — its API deprecations page lists GPT-5.6 Luna as the recommended replacement for two older, separately-deprecating models.
OpenAI self-reports 66.6% on DeepSWE v1.1 (max effort); no independent DeepSWE run for this specific model has appeared yet on deepswe.datacurve.ai or Artificial Analysis's own agent-harness runs (unlike GPT-6 Sol, which AA has run through its Codex-agent harness).
Compare with
FAQ
Has GPT-6 Luna been independently benchmarked?
Partly, one day after launch — three of the eleven benchmarks this site tracks carry an independently-run score: Humanity's Last Exam (38.5%, Artificial Analysis, max effort), ARC-AGI-2 (59.31%, ARC Prize, max tier), and LiveBench (72.0 overall, max effort). GPQA Diamond, SWE-bench Verified, LiveCodeBench, Terminal-Bench 2.1, DeepSWE, Toolathlon-Verified, Agents' Last Exam and HMMT Feb 2026 have none yet — deepswe.datacurve.ai, tbench.ai, toolathlon.xyz, snorkel.ai, matharena.ai and vals.ai were all checked directly.
Is GPT-6 Luna better than GPT-5.6 Luna?
Not measurably. On all three benchmarks where both have independent scores from the same evaluator at max effort, GPT-6 Luna comes out slightly lower — Humanity's Last Exam 38.5% versus 39.5%, LiveBench 72.0 versus 73.6, ARC-AGI-2 59.31% versus 59.6% — and every gap sits inside that benchmark's noise band, so all three are ties. OpenAI's own improvement claim for Luna, 5.4 points on AutomationBench, is on a benchmark this site doesn't track. What clearly changed is price: $0.10/$0.50 versus $0.20/$1.20.
Does GPT-6 Luna's price change with longer prompts?
Yes. The $0.10 input / $0.50 output per-million-token rate applies to prompts up to 272,000 tokens. Once a prompt exceeds that threshold, OpenAI bills the whole request at 2x the input and cached-input rate and 1.5x the output rate — $0.20 input / $0.02 cached / $0.75 output — per developers.openai.com, confirmed 2026-09-23.
Does GPT-6 Luna replace GPT-5.6 Luna?
No. OpenAI's own API deprecations page lists GPT-5.6 Luna as the recommended replacement for two other, older models that are themselves being retired — meaning OpenAI is actively steering traffic toward GPT-5.6 Luna elsewhere on the same site, not away from it. Neither model's page uses "supersede" or "replace" to describe the relationship between them.
How does GPT-6 Luna compare to GPT-6 Sol?
Both launched the same day at the same tiered-pricing structure, but Luna is roughly a twentieth of Sol's price ($0.10/$0.50 versus $2/$10) and scores lower on every independent benchmark this page tracks for both — Humanity's Last Exam 38.5% versus 47.9%, LiveBench 72.0 versus 79.3 overall. OpenAI positions Luna as the cheaper, smaller sibling in the same GPT-6 family as Sol and Astra.
Further reading
- Models with 10M token context windows 2026 — GPT-6 Luna is one of the 31 models it compares.