Head to head
Claude Haiku 5.5 vs GPT-6 Luna
Which is better, Claude Haiku 5.5 or GPT-6 Luna?
Claude Haiku 5.5 finishes ahead of GPT-6 Luna on the index, 87.9 to 84.9, and leads on all four scores: craft, speed, control and value. Both are scored on the same rubric, in the same week, and neither placing is sponsored.
Updated
Claude Haiku 5.5
11 of 73
87.9
A small model priced like a rounding error that scores where mid-tier models did last quarter.
GPT-6 Luna
22 of 73
84.9
The cheap end of GPT-6, and the model free ChatGPT users now talk to.
The four scores, side by side
| Score | Claude Haiku 5.5 | GPT-6 Luna | Difference |
|---|---|---|---|
| Craft | 85 | 80 | +5 |
| Speed | 95 | 93 | +2 |
| Control | 84 | 85 | +1 |
| Value | 95 | 94 | +1 |
| Index score | 87.9 | 84.9 | +3.0 |
Which to pick
Claude Haiku 5.5 is the safer pick on every axis we score. GPT-6 Luna earns its place in the index, but nothing in these four numbers argues for it over Claude Haiku 5.5.
Claude Haiku 5.5
Haiku 5.5 is the cheapest model Anthropic has sold, at ten cents per million input tokens for normal-length prompts, and it scores above GPT-5.6 Terra on the Artificial Analysis index. It is built for classification, extraction, routing and the sub-agents a larger model hands work to. Prompts above 100,000 tokens cost five times as much, so long-document work is not where the bargain is. It is too new to have a human-preference rating yet.
Where it shines
- Ten cents per million input tokens for prompts up to 100,000 tokens
- Scores above mid-tier models from the previous generation
- Million-token window for the jobs that genuinely need it
GPT-6 Luna
Luna is OpenAI's efficiency tier, priced at ten cents per million input tokens with a million-token window and the same structured-output discipline as the rest of the family. Since 7 October it is also what free ChatGPT users get, so for a great many people this model is now what ChatGPT means. It costs half of what GPT-5.6 Luna did for slightly better benchmark scores. Deep reasoning is not its job.
Where it shines
- Ten cents per million input tokens, and a cent for cached input
- The model behind free ChatGPT since October
- Same tool-calling and structured-output behaviour as its larger siblings