Which model is better: Composer 2.5 or GPT-5.6 Luna?

GPT-5.6 Luna is 90.0% cheaper for input tokens ($0.18 vs. $1.80 per 1M tokens) and $0.72 vs. $7.20 for output tokens (10.0x cost difference). In terms of operational performance, GPT-5.6 Luna delivers faster response latency with 90ms TTFT (90ms faster than Composer 2.5). Composer 2.5 leads coding benchmarks at 74.6% SWE-bench vs. 48.5% for GPT-5.6 Luna.
Verified daily via automated API latency tests and official documentation.

Verified Performance & Unit Economics Delta

Daily synchronized metrics from synthetic latency endpoints and benchmark evaluations.

Metric / Dimension Composer 2.5 GPT-5.6 Luna Net Delta / Advantage
Input Cost / 1M Tokens $1.80 $0.18 GPT-5.6 Luna is 10.0x cheaper
Output Cost / 1M Tokens $7.20 $0.72 GPT-5.6 Luna (900% lower)
Avg TTFT Response Latency 180ms 90ms GPT-5.6 Luna (+90ms faster)
SWE-bench Verified (Coding) 74.6% 48.5% Composer 2.5 (+26.1% lead)
Inference Value Score (IVR) 70.4 / 100 99.9 / 100 GPT-5.6 Luna (+29.5 pts)

Interactive Monthly Token Economics & ROI Forecaster

Model your expected production workload across prompt (input) and completion (output) tokens.

Live Calculation Engine
10.0M Tokens
100K 50M 250M 500M+
2.5M Tokens
100K 10M 50M 100M+

Estimated Monthly Spend

Composer 2.5 $5.45

$1.8/1M in · $7.2/1M out

GPT-5.6 Luna $67.50

$0.18/1M in · $0.72/1M out

Projected Monthly Cost Reduction
$62.05 / mo
(91.9% lower cost)
A

When to Choose Composer 2.5

Choose Composer 2.5 when you need Precision multi-file git diff synthesis, automated code review, IDE background indexing, and full-stack repo migration. and have an infrastructure budget aligned with $1.80/1M tokens.

B

When to Choose GPT-5.6 Luna

Choose GPT-5.6 Luna when you need Real-time conversational agents, high-volume classification, intent detection, and low-latency interactive apps. and prioritize OpenAI ecosystem integration at $0.18/1M tokens.

Related Questions & Decision Factors

Which is cheaper: Composer 2.5 or GPT-5.6 Luna?

GPT-5.6 Luna is cheaper at $0.18/1M input tokens compared to $1.80/1M for Composer 2.5.

Which model has lower latency: Composer 2.5 or GPT-5.6 Luna?

GPT-5.6 Luna delivers faster response times with an average TTFT of 90ms vs 180ms for Composer 2.5.

When should you choose Composer 2.5?

Choose Composer 2.5 when you need Precision multi-file git diff synthesis, automated code review, IDE background indexing, and full-stack repo migration. and have an infrastructure budget aligned with $1.80/1M tokens.

When should you choose GPT-5.6 Luna?

Choose GPT-5.6 Luna when you need Real-time conversational agents, high-volume classification, intent detection, and low-latency interactive apps. and prioritize OpenAI ecosystem integration at $0.18/1M tokens.

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