GPT-5.6 Luna vs Claude Haiku 4.5

Pick GPT-5.6 Luna if raw cost per task is your top concern, and pick Claude Haiku 4.5 if you need a HIPAA-ready model with a signed BAA. Both are cheap, fast tiers built for high-volume routine work. Your winner depends on your compliance needs and which vendor you already use.

GPT-5.6 Luna is OpenAI's fastest and most affordable tier. On 2026-07-30 OpenAI cut its price hard, so it now runs at $0.20 input and $1.20 output per million tokens. That makes it one of the lowest-priced frontier tiers on the market.

Claude Haiku 4.5 is Anthropic's small, fast model. It costs more per token than Luna after the cut, but it ships with enterprise compliance options many regulated teams require. This page compares both on price, speed, capability, use cases, and compliance so you can choose by workload.

GPT-5.6 Luna vs. Claude Haiku 4.5: Side-by-Side

Price and value

GPT-5.6 Luna is the cheaper model per token after its 2026-07-30 price cut. Luna now costs $0.20 per million input tokens and $1.20 per million output tokens. Claude Haiku 4.5 costs $1.00 input and $5.00 output per million tokens.

That gap is large. Luna is about 5x cheaper on input and roughly 4x cheaper on output than Haiku 4.5. For very high-volume jobs, that difference adds up fast.

But price per token is not the whole story. Both vendors offer discounts that change the real bill. Anthropic cites up to 90% savings with prompt caching and 50% with batch processing on Haiku 4.5. OpenAI offers prompt caching on GPT-5.6 too.

The right way to compare is cost per finished task, not the sticker price. A model that needs fewer retries or shorter prompts can cost less even at a higher rate. Test both on your own workload before you commit.

• GPT-5.6 Luna: $0.20 input / $1.20 output per million tokens
• Claude Haiku 4.5: $1.00 input / $5.00 output per million tokens
• Both cut costs further with prompt caching; Haiku 4.5 also offers batch savings

→ Compare per-token pricing for every AI model

Speed and latency

Both models are built for speed, and both are fast enough for real-time apps. GPT-5.6 Luna is the fastest tier in OpenAI's GPT-5.6 family. OpenAI says it runs near 9x the speed of frontier-class models from a year ago.

Claude Haiku 4.5 is Anthropic's small, low-latency model. It delivers near-frontier quality at the fast end of Anthropic's lineup. Anthropic positions it for tasks where quick responses matter.

Neither vendor publishes a single head-to-head latency number you can trust across every setup. Real speed depends on prompt size, output length, and your region. Run a timing test on your own traffic to see which feels faster for your use case.

Capability and quality

Both models trade some depth for speed and cost, but each punches above its price tier. GPT-5.6 Luna targets summarization, drafting, classification, and routine automation. OpenAI says Luna outperforms Claude Fable 5 on Agents' Last Exam at a fraction of the cost.

Claude Haiku 4.5 is stronger on coding and agent tasks for a small model. Anthropic pitches it as near-frontier quality at the fast, cheap end of its lineup. It fits developer workflows and multi-step agents that still need low latency.

Neither is a flagship. For the hardest reasoning, coding, or science work, you would step up to GPT-5.6 Sol or a larger Claude model like Opus or Sonnet. Both cheap tiers shine on high-volume, well-scoped tasks, not open-ended deep reasoning.

• GPT-5.6 Luna leans toward summarize, draft, classify, and automate
• Claude Haiku 4.5 leans toward fast coding and low-latency agents
• For hardest tasks, move up to Sol or a larger Claude model

Best use cases for each

GPT-5.6 Luna wins on cost-driven, high-volume text work; Claude Haiku 4.5 wins on fast coding and regulated deployments. Match the model to the job rather than picking one for everything.

Choose GPT-5.6 Luna when you process huge volumes of text and want the lowest token bill. Good fits include support ticket triage, document summarization, tagging, content drafting, and routine back-office automation.

Choose Claude Haiku 4.5 when you need a fast model for coding help, agent steps, or when your industry requires a signed BAA and formal security certifications. It also fits teams already standardized on the Claude API, Bedrock, or Vertex AI.

• GPT-5.6 Luna: high-volume summarizing, classifying, and drafting at lowest cost
• Claude Haiku 4.5: fast coding, agents, and compliance-bound workloads

Compliance and data controls

Claude Haiku 4.5 has the clearer, published compliance story of the two. Anthropic offers a HIPAA-ready configuration with a Business Associate Agreement, plus SOC 2 Type I and Type II, ISO 27001, and ISO 42001 certifications. That matters for healthcare, finance, and other regulated teams.

OpenAI also offers enterprise security controls and signs BAAs for eligible customers under specific terms. But those terms and product scopes change, so confirm the current details for GPT-5.6 Luna directly in OpenAI's trust and compliance docs before you deploy sensitive data.

If a signed BAA or a named certification is a hard requirement, verify it in writing from each vendor. Do not assume a cheap tier inherits every enterprise control. Compliance scope can differ by model, plan, and region.

Where each model runs

GPT-5.6 Luna runs in the OpenAI API and Codex, with no waitlist as of July 2026. That is the simplest path if your stack already uses OpenAI tools.

Claude Haiku 4.5 runs on the Claude API and is also available through AWS Bedrock and Google Vertex AI. That cloud reach helps teams that want to keep AI inside an existing cloud contract and data boundary.

Your platform choice often decides the model. If your data governance is tied to AWS or Google Cloud, Haiku 4.5 may be easier to adopt. If you are already an OpenAI shop, Luna slots in with no new vendor.

The Verdict

There is no single winner here; the right cheap tier depends on your workload and rules. For the lowest cost per high-volume text task, GPT-5.6 Luna is the value leader after its price cut. For fast coding, agent steps, or any project that needs a HIPAA BAA and named certifications, Claude Haiku 4.5 is the safer pick.

A practical approach is to run both on a sample of your real traffic for a week. Measure cost per finished task, latency, and output quality, not just the sticker price. Then let your compliance requirements break any tie. If you want help scoping that test, Layer3 Labs can run a vendor-neutral workflow audit for you.