Budget Tier Showdown
GPT-5.6 Luna vs Gemini 3.5 Flash
Both offer 1M+ context at budget prices. Which delivers more value per dollar?
Last verified: Jul 13, 2026 · See all 67 models ranked →
| Feature | GPT-5.6 Luna | Gemini 3.5 Flash |
|---|---|---|
| Input price (per 1M tokens) | $1.00 | $1.50 |
| Output price (per 1M tokens) | $6.00 | $9.00 |
| Context window | 1.05M tokens | 1M tokens |
| Standard request cost | $0.0039 | $0.00585 |
| Output-heavy request cost | $0.012 | $0.018 |
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OpenAI
GPT-5.6 Luna
$0
estimated monthly cost
Input cost$0
Output cost$0
Per request$0
Google
Gemini 3.5 Flash
$0
estimated monthly cost
Input cost$0
Output cost$0
Per request$0
The Verdict
GPT-5.6 Luna wins on price across the board.
GPT-5.6 Luna ($1/$6) is 33% cheaper than Gemini 3.5 Flash ($1.50/$9) on both input and output. Both offer 1M+ context windows. For most budget-conscious workloads, Luna delivers better value. Gemini 3.5 Flash may have advantages for Google-specific tasks or if you prefer Google's ecosystem.
When to Choose GPT-5.6 Luna
- Cost-first workloads: At $1/$6, Luna is the cheapest 1M+ context model from OpenAI. 33% less than Gemini 3.5 Flash across the board.
- High-volume APIs: For chatbots, content generation, or translation at scale, Luna's 33% price advantage compounds fast.
- OpenAI ecosystem: If you're already using OpenAI's API and want the cheapest 1M+ context option.
When to Choose Gemini 3.5 Flash
- Google ecosystem: If you're already using Google Cloud and want to stay in the GCP ecosystem.
- Google-specific tasks: Gemini may have advantages for tasks involving Google services, multilingual content, or specific training data.
- Established track record: Gemini Flash models have been in production longer and may have more battle-tested reliability.
Cost Comparison: Real-World Scenarios
Chatbot (1,000 requests/day, 1,500 input, 400 output)
GPT-5.6 Luna$117.00/mo
Gemini 3.5 Flash$175.50/mo
Monthly savings$58.50/mo (33%)
Code Generation (200 requests/day, 3,000 input, 1,200 output)
GPT-5.6 Luna$468.00/mo
Gemini 3.5 Flash$702.00/mo
Monthly savings$234.00/mo (33%)
RAG Pipeline (500 queries/day, 5,000 input, 800 output)
GPT-5.6 Luna$390.00/mo
Gemini 3.5 Flash$585.00/mo
Monthly savings$195.00/mo (33%)
Full Comparison Table
| Model | Input/1M | Output/1M | vs GPT-5.6 Luna | Context |
|---|---|---|---|---|
| GPT-5.6 Luna | $1.00 | $6.00 | — | 1.05M |
| Gemini 3.5 Flash | $1.50 | $9.00 | 50% more expensive input, 50% more expensive output | 1M |
| GPT-5.4 mini | $0.75 | $4.50 | 25% cheaper input, 25% cheaper output | 400K |
| DeepSeek V4 Flash | $0.14 | $0.28 | 86% cheaper input, 95% cheaper output | 1M |
| GPT-5.6 Terra | $2.50 | $15.00 | 150% more expensive input, 150% more expensive output | 1.05M |
| Gemini 3.1 Flash-Lite | $0.25 | $1.50 | 75% cheaper input, 75% cheaper output | 1M |
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