OpenAI · AI model API pricing
How much does GPT-5.6 Luna cost?
The fast, light GPT-5.6 tier — a July 2026 repricing cut it five-fold to $0.20/$1.20, putting current-generation OpenAI quality at budget-tier rates.
Rate card
| Input tokens | $0.20 / 1M |
| Cached input | $0.02 / 1M |
| Output tokens | $1.2 / 1M |
| Context window | 1M |
What that means per month
| Workload | Tokens / month | Cost / month |
|---|---|---|
| Prototype | 1M in · 0.3M out | $0.56/mo |
| Small app | 10M in · 3M out | $5.60/mo |
| Production app | 50M in · 15M out | $28/mo |
| High volume | 200M in · 60M out | $112/mo |
| Heavy platform | 1B in · 300M out | $560/mo |
Standard on-demand rates from OpenAI's official pricing page, last checked 2026-07-28. Batch API runs at 50% of these rates. Monthly figures exclude caching and batch discounts. Confirm live pricing before committing.
Where GPT-5.6 Luna sits on price
At the reference month of 10M input and 3M output tokens, GPT-5.6 Luna costs $5.60, which makes it the 4th cheapest of the 30 models tracked here. That is 3.3× the price of Qwen-Flash, the cheapest model at this mix ($1.70). Among the 9 budget-tier models it ranks 4th, behind Qwen-Flash at $1.70.
Cache economics
Cached input on GPT-5.6 Luna bills at $0.02 per 1M — 10% of its own input rate, against a 10% median across the models here that publish a cached-read price. 2 models discount cached reads more steeply than this. On the reference month, serving 80% of that input from cache takes the input side of the bill from $2 to $0.56, leaving output untouched at $3.60 — which is why a high reuse rate changes the ranking above rather than just shaving the total.
Cache reads only. Writes are billed separately by some providers and are excluded here — see the rate note above for OpenAI's terms. Try it at your own hit rate on the AI cost calculator.
Cheaper alternatives
At a reference workload of 10M input / 3M output tokens a month, these cost less than GPT-5.6 Luna ($5.60/mo):
-
Mistral Small 4 $3.30/mo -
Gemini 2.5 Flash-Lite $2.20/mo -
Qwen-Flash $1.70/mo
GPT-5.6 Luna head-to-head
GPT-5.6 Luna price history
- July 2026 · reported OpenAI cuts GPT-5.6 Luna five-fold and drops Terra by 20%
GPT-5.6 Luna fell from $1.00 in / $6.00 out to $0.20 / $1.20 per 1M — a five-fold cut that moves current-generation OpenAI quality into budget-tier pricing. GPT-5.6 Terra dropped from $2.50 / $15.00 to $2.00 / $12.00. Sol, GPT-5.4 Mini and GPT-5.4 Nano were unchanged. Price cuts are rare enough in this category to be worth noting: most 2026 movement has been upward.