Cost per coding-agent request

Is Claude Fable 5 or GPT-5.6 Luna cheaper for coding agents?

For coding agents, Claude Fable 5 costs 39x as much as GPT-5.6 Luna per request ($0.32 vs $0.0084 on our measured traffic), because Claude Fable 5 lists at $10 input, $1 cached input and $50 output per million tokens against $0.20, $0.02 and $1.20 for GPT-5.6 Luna, and GPT-5.6 Luna charges more for prompts over 272K tokens.

List prices: Anthropic pricing, OpenAI API pricing, checked 2026-10-13. Request costs: Standard Compute gateway data, 79,301 coding-agent requests from 75 users, Sep 13 to Oct 12, 2026. How we compute this

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Cost per coding-agent request, side by side

Cost at list price	GPT-5.6 Luna	Fable 5
Prompt under 100K tokens50% of requests, 87% of input cached	$0.0032	$0.16
Prompt of 100K to 272K39% of requests, 88% of input cached	$0.0080	$0.39
Prompt over 272K tokens11% of requests, 86% of input cached	$0.034	$0.87
Average request	$0.0084	$0.32
100 requests	$0.84	$32.47
Median session16 requests; a session ends after 10 idle minutes	$0.092	$4.49
A month of regular usemedian of 20 users active on 5+ days	$11.83	$497

Each logged request priced at the vendor’s list rates for its own token counts, including cache reads and any higher rate for long prompts. Average output: 698 tokens per request.

Benchmarks, speed and latency, side by side

Artificial Analysis	GPT-5.6 Luna	Fable 5
Intelligence Index10 evaluations, 0 to 100	37	50
Terminal-Bench 4.0agentic coding in a terminal	11.6%	42.4%
Output speedmedian	123 tokens/s	67 tokens/s
Time to first answer tokenincludes thinking time	117 s	2.3 min

Source: Artificial Analysis (artificialanalysis.ai). Measured variants: GPT-5.6 Luna (Max), speed on OpenAI; Claude Fable 5 (Max, Opus 4.8 Fallback), speed on Anthropic. Fetched October 13, 2026. Artificial Analysis runs Terminal-Bench 4.0 in its own setup, so its scores differ from the tbench.ai leaderboard.

What to watch for

Claude Fable 5 is superseded: Claude Fable 5.1 costs $0.24 per request. GPT-5.6 Luna is superseded: GPT-6 Luna costs $0.0041 per request. Claude Fable 5 scores clearly higher on the benchmarks above, so it may finish hard tasks in fewer steps.

FAQ

Is GPT-5.6 Luna cheaper than Claude Fable 5 for coding agents?

Yes, at list prices. 100 average coding-agent requests cost $0.84 on GPT-5.6 Luna and $32.47 on Claude Fable 5. A median 16-request session costs $0.092 vs $4.49. Measured on 79,301 real coding-agent requests (Sep 13 to Oct 12, 2026).

How much does a month of Fable 5 vs GPT-5.6 Luna cost?

For the median regular user in our data (1,478 requests in 30 days), about $497 on Claude Fable 5 and $11.83 on GPT-5.6 Luna at list price. Heavier users pay proportionally more.

Claude Fable 5 vs GPT-5.6 Luna: which is better for agents?

Claude Fable 5 scores higher on output quality (9.0/10 vs 7.4/10), while GPT-5.6 Luna is the cheaper option. Claude Fable 5 is best for existing Fable 5 setups that have not yet moved to Fable 5.1 or Opus 5.5; GPT-5.6 Luna is best for cheap subtasks in existing GPT-5.6 setups. Live community votes on this page show what people actually prefer.

Can I switch between Claude Fable 5 and GPT-5.6 Luna in the same agent?

Yes. Model-agnostic agents (Cline, Aider, OpenClaw, Hermes Agent, Kilo Code, OpenCode) let you swap models per task. Many people route hard tasks to the stronger model and routine work to the cheaper one.

Community vote

Pick a winner in each dimension. You can change your vote any time.

Output Quality

Correctness and depth of what it produces

Agentic Ability

Tool calls, instruction-following, and multi-step tasks

Speed

Tokens per second and time-to-first-token

Value for Money

How much capability you get per dollar

Reliability

Consistent results: fewer refusals, loops and format breaks

Every model on this page is included with Standard Compute

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Current frontier models Claude Fable 5.1 · GPT-6 Astra

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