Compare / Gemini 2.5 Flash vs GPT-5.6 Luna
Gemini 2.5 Flash vs GPT-5.6 Luna
Which is cheaper, which is more capable, and which does better at each kind of work, from 12 results on 3 sources that measured both models.
Gemini 2.5 Flash or GPT-5.6 Luna? The short answer
- GPT-5.6 Luna is cheaper: $0.45 against $0.85 per million tokens, 47% less.
- GPT-5.6 Luna scores higher on the Artificial Analysis Intelligence Index: 37.3 against 13.1.
- On our business benchmarks, GPT-5.6 Luna ranks higher for agents and tool use, reasoning and knowledge, writing and sticking to the facts.
At a glance
| Gemini 2.5 Flash | GPT-5.6 Luna | |
|---|---|---|
| Price per million tokens | $0.30 in · $2.50 out | $0.20 in · $1.20 out |
| Blended (3 in : 1 out) | $0.85 | $0.45 |
| Cheapest host, blended | $0.42 (Google AI Studio) | $0.23 (OpenAI) |
| Intelligence Index | 13.1 | 37.3 |
| Spring Prompt overall | – | – |
| Output speed, tokens a second | – | – |
| Context window | 1,048,576 tokens | 1,050,000 tokens |
| Weights | Closed | Closed |
| Developer based in | the US | the US |
Prices are the developer's list price where we have read it, otherwise the typical host on OpenRouter; see every model's price. Intelligence and speed from Artificial Analysis.
Which is better for what
Each model's rank among models available today, for each kind of work, from our own benchmarks and licensed sources. The better rank is in green.
| Use case | Gemini 2.5 Flash | GPT-5.6 Luna |
|---|---|---|
| Agents and tool useMulti-step tasks with tools: support desks, coding agents, function calls | 74 of 161 | 47 of 161 |
| Professional workReal tasks from banking, consulting and law, business documents and freelance projects | not measured | 20 of 51 |
| Reasoning and knowledgeHard questions across science, maths and general knowledge | 115 of 195 | 38 of 195 |
| WritingWhat people prefer in blind comparisons, and judged writing quality | 93 of 187 | 57 of 187 |
| Sticking to the factsSummarising without inventing things, and factual answers | 66 of 153 | 59 of 153 |
Every shared result
| Benchmark | Metric | Gemini 2.5 Flash | GPT-5.6 Luna |
|---|---|---|---|
| Arena (formerly LMArena)reported | OverallArena rating | 1,437 | 1,461 |
| Arena (formerly LMArena)reported | Business, management and financeArena rating | 1,399 | 1,463 |
| Arena (formerly LMArena)reported | Creative writingArena rating | 1,394 | 1,412 |
| Arena (formerly LMArena)reported | Expert promptsArena rating | 1,424 | 1,491 |
| Arena (formerly LMArena)reported | Instruction followingArena rating | 1,400 | 1,446 |
| Arena (formerly LMArena)reported | OverallArena rating | 1,409 | 1,454 |
| Arena (formerly LMArena)reported | Writing, literature and languageArena rating | 1,402 | 1,435 |
| Artificial Analysisreported | Artificial Analysis Intelligence Indexindex score | 13.1 | 37.3 |
| Artificial Analysisreported | GPQA Diamond% of questions | 79.0% | 91.1% |
| Artificial Analysisreported | Humanity's Last Exam% of questions | 12.1% | 39.5% |
| Artificial Analysisreported | Long-context reasoning (AA-LCR)% of questions | 65.3% | 83.7% |
| Vending-Bench 2reported | Money after a yearUS dollars | $548.84 | $4,094.71 |
Bold green marks the better value on that metric. Where a source reports ranges that overlap, the difference may not be meaningful; see the benchmark page for ranges.
Quick answers
Is Gemini 2.5 Flash better than GPT-5.6 Luna?
It depends on the task. Among models available today, on our benchmarks and licensed sources, GPT-5.6 Luna ranks higher for agents and tool use, reasoning and knowledge, writing and sticking to the facts.
Which is cheaper, Gemini 2.5 Flash or GPT-5.6 Luna?
GPT-5.6 Luna costs $0.45 per million tokens (three input to one output), against $0.85 for Gemini 2.5 Flash.
Run Gemini 2.5 Flash and GPT-5.6 Luna on your own prompt
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