{"slug": "costs-of-online-llm-usage", "title": "Costs of Online LLM Usage", "summary": "Spec-driven development on OpenRouter cut the cost of evaluating a Markdown prompt of up to 180 lines and generating a function to between 1 and 7 cents, according to the author's experiments, far below a coding harness such as OpenCode because less context is required. GPT-6-Sol evaluated a 180-line prompt for 5 cents while Kimi-K3 evaluated a shorter prompt for 32 cents, a gap the author attributes to GPT-6-Sol generating fewer thinking tokens. GLM 5.3 Flash and MiMo-V2.6 Flash were the cheapest options tested, generating output for a tiny fraction of a cent at their per-token prices.", "body_md": "Over the past few months I have been trying to understand how to use **LLMs** **cost-effectively** on OpenRouter. AI bills can quickly become excessive. And with agentic coding, code quality can deteriorate as costs go sky-high.\n\nUsing **spec-driven** development—where one writes a spec, and then has an agent implement it in **chat**—can **lower costs**. In many of my experiments, costs were between 1 and 7 cents to evaluate a Markdown prompt (up to 180 lines) and generate a function. This is significantly less expensive than a coding harness like OpenCode—less context is needed.\n\nBesides generating code from specifications, using **cheaper models** (cost per million tokens) is beneficial. For example, GLM 5.3 Flash and MiMo-V2.6 Flash were much cheaper for code generation.\n\n• GPT-6-Sol evaluated a 180-line prompt for 5 cents, while Kimi-K3 evaluated a shorter prompt for 32 cents—the difference is that GPT generated fewer thinking tokens.\n\n• GLM 5.3 Flash and MiMo-V2.6 Flash had such low per-token costs that they could generate output for a tiny fraction of a cent.\n\n• GPT-6-Sol, because it was more frugal with thinking tokens, was cheaper than Kimi-K3; the cheapest options were GLM 5.3 Flash and MiMo-V2.6 Flash.", "url": "https://wpnews.pro/news/costs-of-online-llm-usage", "canonical_source": "https://www.dotnetperls.com/2026_9_26_costs-online-llm-usage", "published_at": "2026-09-26 07:00:00+00:00", "updated_at": "2026-09-26 13:58:55.203910+00:00", "lang": "en", "topics": ["large-language-models", "ai-tools", "ai-agents", "developer-tools"], "entities": ["OpenRouter", "OpenCode", "GPT-6-Sol", "Kimi-K3", "GLM 5.3 Flash", "MiMo-V2.6 Flash"], "also_reported_by": [], "alternates": {"html": "https://wpnews.pro/news/costs-of-online-llm-usage", "markdown": "https://wpnews.pro/news/costs-of-online-llm-usage.md", "text": "https://wpnews.pro/news/costs-of-online-llm-usage.txt", "jsonld": "https://wpnews.pro/news/costs-of-online-llm-usage.jsonld"}}