Gemini 4 Argon vs GPT-5.6 Luna: pricing and benchmarks
GPT-5.6 Luna is 90% cheaper on input tokens ($0.20 vs $2.00 per 1M). GPT-5.6 Luna is 88% cheaper on output tokens ($1.20 vs $10.00 per 1M). On our document Q&A workload (50,000 questions a month), GPT-5.6 Luna costs $116.00 a month versus $1,100 for Gemini 4 Argon, 89% less. Gemini 4 Argon scores 164.6 on the Epoch Capabilities Index vs 156.3 for GPT-5.6 Luna.
Prices verified October 17, 2026.
Which should you choose?
Gemini 4 Argon scores 164.6 on the Epoch Capabilities Index vs 156.3 for GPT-5.6 Luna.
Gemini 4 Argon scores 86.0% on FrontierMath (Tiers 1–3) vs 82.1% for GPT-5.6 Luna.
GPT-5.6 Luna costs $0.45 per 1M tokens (3:1 input-to-output mix) vs $4.00 for Gemini 4 Argon, 89% less.
A trade-off: Gemini 4 Argon is 8.2 ECI points more capable but costs 8.9x as much as GPT-5.6 Luna.
Pricing and specs
| Gemini 4 Argon | GPT-5.6 Luna | |
|---|---|---|
| Provider | OpenAI | |
| API model ID | gemini-4-argon | gpt-5.6-luna |
| Input / 1M tokens | $2.00 | $0.20 |
| Cached input / 1M tokens | $0.10 | $0.02 |
| Output / 1M tokens | $10.00 | $1.20 |
| Long-context rates | — | $0.40 in / $1.80 out on long-context requests |
| Context window | 1.05M tokens | 1.05M tokens |
| Max output | 66K tokens | 128K tokens |
| Batch discount | 50% off | 50% off |
Benchmarks
| Gemini 4 Argon | GPT-5.6 Luna | |
|---|---|---|
| Epoch Capabilities Index | 164.6 | 156.3 |
| GPQA Diamond· Science reasoning | 96.4% | 91.6% |
| FrontierMath (Tiers 1–3)· Advanced math | 86.0% | 82.1% |
| SimpleQA Verified· Factual accuracy | 76.0% | 41.0% |
| ARC-AGI-2· Abstract reasoning | — | 59.5% |
| DeepSWE· Coding | — | 67.2% |
| APEX-Agents· Agentic work | 82.4% | 43.0% |
Source: Epoch AI, best recorded result per model (CC BY 4.0). A dash means no published score. See all benchmarks
Monthly cost for real workloads
| Workload | Gemini 4 Argon | GPT-5.6 Luna | Difference |
|---|---|---|---|
Support chatbot 100,000 replies a month, ~1,500 input tokens (system prompt + history) and ~400 output tokens each. | $700.00 | $78.00 | GPT-5.6 Luna 89% cheaper |
Document Q&A (RAG) 50,000 questions a month with ~8,000 tokens of retrieved context and ~600 output tokens each. | $1,100 | $116.00 | GPT-5.6 Luna 89% cheaper |
Coding agent 10,000 agent steps a month, ~40,000 input tokens each (70% read from the prompt cache) and ~2,000 output tokens. | $468.00 | $53.60 | GPT-5.6 Luna 89% cheaper |
Estimates use standard list prices and ignore cache-write surcharges. Different tokenizers can count the same text differently, so test with your own prompts.
Gemini 4 Argon vs GPT-5.6 Luna cost calculator
- $116.00/mo$0.0023 / request
- Gemini 4 ArgonGoogle$1,100/mo$0.02 / request
Standard-tier list prices. Long-context rates apply automatically where the provider publishes a threshold. Excludes cache-write surcharges, taxes, batch and volume discounts.
Gemini 4 Argon pricing notes
Google’s flagship reasoning model for complex coding, agents, math and science.
- Introductory price through November 30, 2026. From December 1, 2026: $4 input, $0.20 cached, $20 output per 1M tokens.
- Not available on the Gemini API free tier.
- Output price includes thinking tokens.
- Max output is 65,536 tokens by default and up to 1,048,576 with long decode.
- Implicit caching only; explicit context caching is not supported.
- Priority inference costs 1.8x the standard rate.
GPT-5.6 Luna pricing notes
The GPT-5.6 model optimized for cost-sensitive, high-volume workloads.
- Cache writes are billed at $0.25 per 1M tokens.
- Fast mode costs 2x the standard rate; Flex costs half.
Frequently asked questions
- Is Gemini 4 Argon cheaper than GPT-5.6 Luna?
- GPT-5.6 Luna is 90% cheaper on input tokens ($0.20 vs $2.00 per 1M). GPT-5.6 Luna is 88% cheaper on output tokens ($1.20 vs $10.00 per 1M). On our document Q&A workload (50,000 questions a month), GPT-5.6 Luna costs $116.00 a month versus $1,100 for Gemini 4 Argon, 89% less.
- Which is more capable, Gemini 4 Argon or GPT-5.6 Luna?
- Gemini 4 Argon scores 164.6 on the Epoch Capabilities Index vs 156.3 for GPT-5.6 Luna.
- How much does Gemini 4 Argon cost per 1M tokens?
- Gemini 4 Argon costs $2.00 per 1M input tokens and $10.00 per 1M output tokens, and $0.10 per 1M cached input tokens on Google’s standard tier.
- How much does GPT-5.6 Luna cost per 1M tokens?
- GPT-5.6 Luna costs $0.20 per 1M input tokens and $1.20 per 1M output tokens, and $0.02 per 1M cached input tokens on OpenAI’s standard tier.
- Which has the larger context window, Gemini 4 Argon or GPT-5.6 Luna?
- GPT-5.6 Luna has the larger context window: 1.05M tokens versus 1.05M for Gemini 4 Argon.