Claude Haiku 5.5 vs GPT-6 Instant: Lightweight Speed Models Compared

Anthropic released Claude Haiku 5.5 on October 7 for high-volume, cost-sensitive tasks such as summarization, classification, database queries and agent subtasks; the same day, OpenAI rolled GPT-6 out to all ChatGPT users, with the Instant tier aimed at starting answers to web-search questions faster.

Both are publicly priced in the same tier: $0.10 per million input tokens and $0.50 per million output tokens (Haiku 5.5 caps the rate at prompts up to 100K tokens; GPT-6's figure is the published Luna-tier API price).

The table below places the two side by side on pricing structure, context window, speed claims and published benchmarks: all benchmark figures are vendor-reported, and no independent head-to-head test exists yet.

1. Release and availability: Haiku 5.5 launched October 7 with model ID claude-haiku-5-5 and is available on Claude's free tier; GPT-6 rolled out to paid users October 7 and to Free and Go users (Luna tier) October 8.
2. Pricing structure: Haiku 5.5 costs $0.50/$2.50 past 100K prompt tokens, about 5x the headline tier, with $0.01 cache reads; GPT-6's Luna-tier API pricing covers up to 272K input tokens.
3. Context window: Haiku 5.5 offers a 1M-token context window with 128K max output; GPT-6's Luna-tier API supports up to 272K input tokens.
4. Benchmarks (vendor-reported): In Anthropic's official table, Haiku 5.5 scores 72.4% on the OSWorld 2.1 offline subset vs 48.9% for GPT-6 Luna, and 39.2% vs 16.4% on Terminal-Bench 4.0. OpenAI says GPT-6 Instant starts answering web-search questions 44% faster on average than GPT-5.6 Instant, and that its Extra High reasoning tier matches GPT-5.6's Medium tier speed on common agentic tasks.
5. No independent testing: No third party has published head-to-head speed or benchmark results for the two; press coverage notes all figures in Anthropic's table come from the vendor with no independent reproduction yet.