Which model is better: Fable 5 or GPT-5.6 Luna?

GPT-5.6 Luna is 91.0% cheaper for input tokens ($0.18 vs. $2.00 per 1M tokens) and $0.72 vs. $8.00 for output tokens (11.1x cost difference). In terms of operational performance, GPT-5.6 Luna delivers faster response latency with 90ms TTFT (150ms faster than Fable 5). Fable 5 leads coding benchmarks at 58.0% 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 Fable 5 GPT-5.6 Luna Net Delta / Advantage
Input Cost / 1M Tokens $2.00 $0.18 GPT-5.6 Luna is 11.1x cheaper
Output Cost / 1M Tokens $8.00 $0.72 GPT-5.6 Luna (1011.1% lower)
Avg TTFT Response Latency 240ms 90ms GPT-5.6 Luna (+150ms faster)
SWE-bench Verified (Coding) 58% 48.5% Fable 5 (+9.5% lead)
Inference Value Score (IVR) 59.8 / 100 99.9 / 100 GPT-5.6 Luna (+40.1 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

Fable 5 $5.45

$2/1M in · $8/1M 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 Fable 5

Choose Fable 5 when you need Long-horizon multi-agent world simulations, narrative engine synthesis, interactive character memory, and creative reasoning. and have an infrastructure budget aligned with $2.00/1M 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: Fable 5 or GPT-5.6 Luna?

GPT-5.6 Luna is cheaper at $0.18/1M input tokens compared to $2.00/1M for Fable 5.

Which model has lower latency: Fable 5 or GPT-5.6 Luna?

GPT-5.6 Luna delivers faster response times with an average TTFT of 90ms vs 240ms for Fable 5.

When should you choose Fable 5?

Choose Fable 5 when you need Long-horizon multi-agent world simulations, narrative engine synthesis, interactive character memory, and creative reasoning. and have an infrastructure budget aligned with $2.00/1M 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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