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Claude Opus 5 vs GPT-5.6 Luna

Side-by-side API economics and benchmarks. Per-1M input and output rates, context window, and verified metrics.

Tale of the tape

Head-to-head specs pulled from each model profile.

Metric Claude Opus 5 GPT-5.6 Luna
Input cost / 1M $5.00 $0.20
Output cost / 1M $25.00 $1.20
Context window 1,000,000 tokens 1,050,000 tokens
MMLU score

Cost verdict

Enter monthly input and output volumes to see total cost savings.

Claude Opus 5

Input: 1M × $5.00 = $5.00
Output: 1M × $25.00 = $25.00
Total
$30.00

GPT-5.6 Luna

Input: 1M × $0.20 = $0.20
Output: 1M × $1.20 = $1.20
Total
$1.40

Total cost savings

$28.60

GPT-5.6 Luna saves $28.60 per month vs the other model at this volume.

Model routing savings

Uses this page's verified rates. Claude Opus 5 is the premium route (higher combined per-1M cost); GPT-5.6 Luna handles routine traffic.

Premium model

Claude Opus 5

$5.00 in · $25.00 out / 1M

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Economical model

GPT-5.6 Luna

$0.20 in · $1.20 out / 1M

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All premium

Claude Opus 5

$1,500.00

100% of input and output on the premium route

Routed stack

80%GPT-5.6 Luna

Claude Opus 5

$356.00

Routine slice
$56.00
Premium slice
$300.00

Monthly savings

$1,144.00

76.3% lower

Rates pulled from this page's model database entries (claude-opus-5, gpt-5-6-luna) — same per-1M input/output figures as Tale of the tape. Production routing needs quality gates and monitoring.

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