GPT-5.6 Luna vs Claude Haiku 4.5
OpenAI's GPT-5.6 Luna and Anthropic's Claude Haiku 4.5 both target production language workloads, but they price and behave differently. Here is the side-by-side.
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The short answer
GPT-5.6 Luna is the cheaper option — roughly 4.4x less on a blended workload, and it suits high-volume work on a tight budget. Claude Haiku 4.5 justifies its premium when you need lowest-latency claude responses.
OpenAI • GPT-5.6
$0.20 / $1.20
/ 1M tokens (input / output)
After an 80% price cut in July 2026, Luna became the value outlier among frontier-family models: it outperforms the previous generation's top-end Opus tier on coding evals while costing about a fiftieth of Fable 5 per input token. This is the model to route bulk traffic through in a tiered architecture.
Anthropic • Claude 4.5
$1.00 / $5.00
/ 1M tokens (input / output)
The fastest model Anthropic ships, still on the Claude 4.5 generation with a 200K window and an early-2025 knowledge cutoff. Worth it when response latency is the product requirement; otherwise Sonnet 5 offers more capability and five times the context for twice the price.
Input price
Claude Haiku 4.5 is 5.0x the price than GPT-5.6 Luna on input tokens.
Output price
Claude Haiku 4.5 is 4.2x the price than GPT-5.6 Luna on output tokens — usually the side that dominates the bill.
Monthly cost at three workload sizes
Standard (non-batch, non-cached) rates. Reasoning models will exceed these figures because thinking tokens bill as output.
| Workload | GPT-5.6 Luna | Claude Haiku 4.5 | Difference |
|---|---|---|---|
| Light — 1M in / 200K out | $0 | $2 | $2 |
| Moderate — 10M in / 2M out | $4 | $20 | $16 |
| Heavy — 100M in / 20M out | $44 | $200 | $156 |
Specification comparison
| Attribute | GPT-5.6 Luna | Claude Haiku 4.5 |
|---|---|---|
| Input (/ 1M tokens) | $0.20 | $1.00 |
| Output (/ 1M tokens) | $1.20 | $5.00 |
| Cached input | $0.02 | $0.10 |
| Context window | 1,048,576 tokens | 200,000 tokens |
| Max output | 128,000 tokens | 64,000 tokens |
| Native reasoning | Yes | Yes |
| Knowledge cutoff | 2026-02 | 2025-02 |
| Relative latency | low | low |
| Open weights | No | No |
| API model ID | gpt-5.6-luna | claude-haiku-4-5 |
| Status | stable | stable |
GPT-5.6 Luna: Cut 80% from the $1/$6 launch price on 2026-07-30.
Choose GPT-5.6 Luna if…
- Classification and content moderation
- High-frequency agent subtasks
- Bulk summarization
- Cost-sensitive chat features
Choose Claude Haiku 4.5 if…
- Real-time chat suggestions
- Lightweight extraction and tagging
- Guardrail and routing calls
- High-frequency background jobs
Frequently asked
Is GPT-5.6 Luna or Claude Haiku 4.5 cheaper?
GPT-5.6 Luna is cheaper. On a blended 3:1 input-to-output workload it costs about 4.4x less than Claude Haiku 4.5.
Which has the larger context window, GPT-5.6 Luna or Claude Haiku 4.5?
GPT-5.6 Luna has the larger window at 1.05M tokens versus 200K.
Should I use GPT-5.6 Luna or Claude Haiku 4.5?
Pick GPT-5.6 Luna for high-volume work on a tight budget. Pick Claude Haiku 4.5 for lowest-latency claude responses. If cost dominates the decision, GPT-5.6 Luna wins; if you need the capability ceiling, benchmark both on your own evals before committing.