GPT-5.6 Luna vs Gemini 3.6 Flash — LLM API Cost Comparison
Compare GPT-5.6 Luna (OpenAI) vs Gemini 3.6 Flash (Google) on cost per million tokens, context window, and monthly spend.
Prices verified 2026-08-03 · Pricing may change — use the calculator for current estimates
- Input
- $0.2/1M tokens
- Output
- $1.2/1M tokens
- Context
- 1M tokens
- Released
- 2026-07
OpenAI cost-sensitive GPT-5.6 tier; 1.05M context
- Input
- $1.5/1M tokens
- Output
- $7.5/1M tokens
- Context
- 1M tokens
- Released
- 2026-07
Latest stable Gemini Flash; agentic and multimodal workloads; 1M context
Monthly Cost by Usage Tier (70% input / 30% output ratio)
| Usage | GPT-5.6 Luna | Gemini 3.6 Flash | Cheaper by |
|---|---|---|---|
| Light (1M tokens) | $0.500 | $3.30 | GPT-5.6 Luna (85%) |
| Moderate (10M tokens) | $5.00 | $33.00 | GPT-5.6 Luna (85%) |
| Heavy (100M tokens) | $50.00 | $330 | GPT-5.6 Luna (85%) |
| Very Heavy (1B tokens) | $500 | $3,300 | GPT-5.6 Luna (85%) |
Frequently Asked Questions
Which is cheaper — GPT-5.6 Luna or Gemini 3.6 Flash?
For input tokens, GPT-5.6 Luna is cheaper at $0.2/1M tokens — 7.5× less than $1.5/1M. For output tokens, GPT-5.6 Luna wins at $1.2/1M vs $7.5/1M. At heavy workloads (100M tokens/month), the cost difference can be significant.
What is the context window difference between GPT-5.6 Luna and Gemini 3.6 Flash?
GPT-5.6 Luna supports 1,050,000 tokens per request; Gemini 3.6 Flash supports 1,048,576 tokens. GPT-5.6 Luna wins on context length, making it better for long documents, large codebases, or extended conversations without chunking.
When should I choose GPT-5.6 Luna over Gemini 3.6 Flash?
Choose GPT-5.6 Luna (OpenAI) if you prefer OpenAI's ecosystem, tooling, or reliability track record. OpenAI cost-sensitive GPT-5.6 tier; 1.05M context. Choose Gemini 3.6 Flash (Google) if Latest stable Gemini Flash; agentic and multimodal workloads; 1M context. the price/performance fits your workload better. Use this calculator to find the break-even point for your exact token volume.
How much does 1 billion tokens cost on GPT-5.6 Luna vs Gemini 3.6 Flash?
At 700M input + 300M output tokens (1B total): GPT-5.6 Luna costs $500; Gemini 3.6 Flash costs $3300. The difference is $2800/billion tokens at this 70/30 input/output ratio.