Cost per coding-agent request

Is GPT-5.6 Luna or GPT-5.6 Terra cheaper for coding agents?

For coding agents, GPT-5.6 Terra costs 10.0x as much as GPT-5.6 Luna per request ($0.084 vs $0.0084 on our measured traffic), because GPT-5.6 Terra lists at $2 input, $0.20 cached input and $12 output per million tokens against $0.20, $0.02 and $1.20 for GPT-5.6 Luna, and both charge more for long prompts.

List prices: 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	GPT-5.6 Terra
Prompt under 100K tokens50% of requests, 87% of input cached	$0.0032	$0.032
Prompt of 100K to 272K39% of requests, 88% of input cached	$0.0080	$0.080
Prompt over 272K tokens11% of requests, 86% of input cached	$0.034	$0.34
Average request	$0.0084	$0.084
100 requests	$0.84	$8.40
Median session16 requests; a session ends after 10 idle minutes	$0.092	$0.92
A month of regular usemedian of 20 users active on 5+ days	$11.83	$118

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	GPT-5.6 Terra
Intelligence Index10 evaluations, 0 to 100	37	42
Terminal-Bench 4.0agentic coding in a terminal	11.6%	35.4%
Output speedmedian	123 tokens/s	135 tokens/s
Time to first answer tokenincludes thinking time	117 s	2.2 min

Source: Artificial Analysis (artificialanalysis.ai). Measured variants: GPT-5.6 Luna (Max), speed on OpenAI; GPT-5.6 Terra (Max), speed on OpenAI. 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

GPT-5.6 Luna is superseded: GPT-6 Luna costs $0.0041 per request. GPT-5.6 Luna scores close to it on the benchmarks above, so the cheaper request is not bought with much lower ability.

FAQ

Is GPT-5.6 Luna cheaper than GPT-5.6 Terra for coding agents?

Yes, at list prices. 100 average coding-agent requests cost $0.84 on GPT-5.6 Luna and $8.40 on GPT-5.6 Terra. A median 16-request session costs $0.092 vs $0.92. Measured on 79,301 real coding-agent requests (Sep 13 to Oct 12, 2026).

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

For the median regular user in our data (1,478 requests in 30 days), about $118 on GPT-5.6 Terra and $11.83 on GPT-5.6 Luna at list price. Heavier users pay proportionally more.

GPT-5.6 Luna vs GPT-5.6 Terra: which is better for agents?

GPT-5.6 Terra scores higher on output quality (8.0/10 vs 7.4/10), while GPT-5.6 Luna is the cheaper option. GPT-5.6 Luna is best for cheap subtasks in existing GPT-5.6 setups; GPT-5.6 Terra is best for fast mid-tier work in existing GPT-5.6 setups. Live community votes on this page show what people actually prefer.

Can I switch between GPT-5.6 Luna and GPT-5.6 Terra 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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