Claude Sonnet 5.5 (Max, Default Fallback) vs GPT-5.6 Luna (Low)

Which is better for the money: Claude Sonnet 5.5 (Max, Default Fallback) by Anthropic or GPT-5.6 Luna (Low) by OpenAI? Intelligence, total benchmark cost, and end-to-end time from Artificial Analysis & other sources, snapshot 2026-10-26.

Trade-off

AnthropicClaude Sonnet 5.5 (Max, Default Fallback)Off the frontier

Intelligence: 56.00
Total cost: $7260

OpenAIGPT-5.6 Luna (Low)Off the frontier

Intelligence: 21.00
Total cost: $27.0

Verdict

Depends on your budget

Claude Sonnet 5.5 (Max, Default Fallbac… scores 35.0 points higher (56.0 vs 21.0) but costs 269× as much to run the benchmark ($7260 vs $27.0; flagship vs budget cost classes). They are not alternatives at one budget: pick Claude Sonnet 5.5 (Max, Default Fallbac… when you need intelligence above 21.0, and GPT-5.6 Luna (Low) when 21.0 is enough.

Metric	Claude Sonnet 5.5 (Max, Default Fallback)	GPT-5.6 Luna (Low)	Difference
Intelligence (higher is better)	56.0	21.0	−62.5% GPT-5.6 Luna (Low) is 62.5% less intelligent
Total AA cost (lower is better)	$7,259.50	$27.02	−99.6% GPT-5.6 Luna (Low) is 99.6% cheaper
End-to-end time (lower is better)	465.48s	5.78s	−98.8% GPT-5.6 Luna (Low) is 98.8% faster
Price per 1M tokens (in / out)	$2.00 / $10.0	$0.20 / $1.20
Input modalities	Text, Image	Text, Image

GPT-5.6 Luna (Low) vs Claude Sonnet 5.5 (Max, Default Fallback): 62.5% less intelligence, 99.6% less cost to run the AA benchmark, and 98.8% faster end-to-end.

Open this matchup in the interactive picker Claude Sonnet 5.5 (Max, Default Fallback): what beats it GPT-5.6 Luna (Low): what beats it

Today's Pareto frontier

Against the frontier

Claude Sonnet 5.5 (Max, Default Fallback) is off the frontier: at the same or lower cost, Claude Opus 5.5 (Xhigh, Default Fallback) scores 56.00 for $4057.
GPT-5.6 Luna (Low) is off the frontier: at the same or lower cost, GPT-6 Luna (Low) scores 21.50 for $10.6.

Claude Sonnet 5.5 (Max, Default Fallback)GPT-5.6 Luna (Low)Today's Pareto frontierEvery other model

Matchup

Compare something else

Agents: Accept: text/markdown or ?format=md returns this page as Markdown. JSON: /api/v1/compare/claude-sonnet-5-5/gpt-5-6-luna-low · Markdown: /api/v1/compare/claude-sonnet-5-5/gpt-5-6-luna-low?format=md · llms.txt · agent skill