OpenAI API Pricing: GPT-5.6 Rates per 1M Tokens
Short answer: OpenAI's GPT-5.6 family costs $0.20–$4.00 per 1M input tokens and $1.20–$20.00 per 1M output tokens. All three models share a 1,050,000-token context window — and a long-context surcharge that kicks in above 272K input tokens.
GPT-5.6 pricing table
Standard on-demand text rates per 1,000,000 tokens, verified against OpenAI's official model docs on 2026-08-23.
| Model | Input / 1M | Output / 1M | Context window | Max output | Source |
|---|---|---|---|---|---|
GPT-5.6 Sol Flagship reasoning | $4.00 | $20.00 | 1,050,000 | 128,000 | OpenAI |
GPT-5.6 Terra Balanced mid-tier | $2.00 | $12.00 | 1,050,000 | 128,000 | OpenAI |
GPT-5.6 LunaLowest Budget / high-volume | $0.20 | $1.20 | 1,050,000 | 128,000 | OpenAI |
GPT-5.6 Sol's $4.00/$20.00 rates are promotional from Aug 21, 2026 through at least Nov 21, 2026 (previously $5.00/$30.00). Prices are informational estimates in USD per OpenAI-published token rates and may exclude caching, batch discounts, tools or taxes. Prompts over 272K input tokens bill at higher long-context rates. The OpenAI invoice is the source of truth.
The 272K long-context surcharge, in real numbers.
Every GPT-5.6 model shares the same rule: once a prompt exceeds 272,000 input tokens, the entire request moves to long-context rates — 2x input price, 1.5x output price. It is not a marginal rate on the overflow; the whole request reprices.
Worked example on GPT-5.6 Terra: a 300K-token document plus a 2K-token answer costs $0.62 at standard rates, but $1.24 once the surcharge applies — roughly double. On GPT-5.6 Sol the same request jumps from $1.24 to $2.46. If your workload regularly sends large repositories or long transcripts, model the surcharge before committing — the calculator below applies it automatically.
Your workload on GPT-5.6, priced monthly
Pick a preset or enter per-request token volumes and daily requests. The long-context surcharge applies automatically above 272K input tokens.
| Model | Per request | Per day | 30-day estimate |
|---|
Which GPT-5.6 model fits which workload?
Purely on arithmetic: at chatbot volumes (2K in / 500 out per request, 5K requests a day) GPT-5.6 Luna runs about $150/month where Sol costs $2,700 — an 18x spread for the same token volumes. Luna handles classification, extraction, short answers and high-volume chat at the lowest rates; Terra is the balanced default for mixed workloads; Sol is reserved for hard reasoning where output quality justifies the premium.
"Best fit" here is a cost result, not a quality ranking — benchmark quality on your own prompts before routing production traffic. Compare OpenAI against the other providers on the LLM API Pricing Comparison page.
Recent OpenAI pricing changes
OpenAI API pricing questions
How much does the OpenAI API cost?
OpenAI GPT-5.6 models cost $0.20–$4.00 per 1M input tokens and $1.20–$20.00 per 1M output tokens at standard rates: GPT-5.6 Luna at $0.20/$1.20, GPT-5.6 Terra at $2.00/$12.00, and GPT-5.6 Sol at $4.00/$20.00 (promotional through at least Nov 21, 2026).
What is the cheapest OpenAI API model?
GPT-5.6 Luna is the cheapest OpenAI model at $0.20 per 1M input and $1.20 per 1M output tokens — 20x cheaper than the flagship GPT-5.6 Sol on input — while keeping the same 1,050,000-token context window.
What is the OpenAI long-context pricing rule?
On GPT-5.6 models, prompts over 272K input tokens are billed at higher long-context rates: 2x the standard input price and 1.5x the standard output price. A 300K-token prompt on GPT-5.6 Terra therefore costs about $1.20 in input instead of $0.60.
Does OpenAI offer API discounts?
Yes. OpenAI discounts repeated prompt prefixes through prompt caching and offers lower rates for non-urgent jobs through the Batch API on supported models. The rates on this page are standard on-demand prices, so heavy workloads with caching or batch usually cost less.
How does OpenAI pricing compare to Claude and Gemini?
GPT-5.6 Luna ($0.20/$1.20) is the cheapest tracked model from any of the three providers. At flagship level, GPT-5.6 Sol ($4.00/$20.00, promotional through at least Nov 21, 2026) now undercuts Claude Opus 5 ($5.00/$25.00) on both input and output. See the full side-by-side table on the LLM API Pricing Comparison page, or the Claude and Gemini deep dives.
Where these numbers come from.
All rates are taken from OpenAI's official model documentation and re-verified weekly. The calculator multiplies your token volumes by published per-million-token rates and applies the documented 272K long-context surcharge; it does not estimate tokenization and does not apply caching or batch discounts.
Official sources: GPT-5.6 Sol, GPT-5.6 Terra, GPT-5.6 Luna. Always confirm the OpenAI invoice before making purchasing decisions.