Head to head
vs Claude Sonnet 4 is retired.
For light moderate heavy
No verdict
One cost is measured and the other is stale . The two bases are never ranked against each other, so no verdict is given. Each figure is shown on its own basis below.
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Verified pricing, pass rate and cost per solved task for GPT-5.6 Luna and Claude Sonnet 4 Figure GPT-5.6 Luna Claude Sonnet 4 Input $/Mtok $0.2 $3 Output $/Mtok $1.2 $15 Cached input $/Mtok $0.02 $0.3 Pass rate 57% 61% Cost per solved task $2.65 measured $1.96 stale Cost per month $530 $392
Cost per month against tasks per month · drag the marker
Monthly cost against tasks per month Log-log lines for Claude Sonnet 4 (stale, $1.96 per solved task), GPT-5.6 Luna (measured, $2.65 per solved task) from 10 to 100,000 tasks a month. Marker at 200 tasks. 10 100 1k 10k 100k $100 $1k $10k $100k TASKS / MONTH (log) → 200 tasks Claude Sonnet 4 · STALE · $1.96 per solved task $392 Claude Sonnet 4 STALE GPT-5.6 Luna · MEASURED · $2.65 per solved task $530 GPT-5.6 Luna MEASURED Monthly cost against tasks per month Log-log lines for Claude Sonnet 4 (stale, $1.96 per solved task), GPT-5.6 Luna (measured, $2.65 per solved task) from 10 to 100,000 tasks a month. Marker at 200 tasks. 10 100 1k 10k 100k $100 $1k $10k $100k TASKS / MONTH (log) → 200 tasks Claude Sonnet 4 · STALE · $1.96 per solved task $392 GPT-5.6 Luna · MEASURED · $2.65 per solved task $530 — Claude Sonnet 4 · STALE — GPT-5.6 Luna · MEASURED Solid measured · dashed modeled · dotted stale. The gap is the verdict.
Source: Artificial Analysis (artificialanalysis.ai) · verified 2026-08-21 · prices from each provider's pricing page; measured rows ignore the tier · Methodology · All models at these settings