GPT-5.6 Luna vs Gemini 3.5 Flash-Lite
GPT-5.6 Luna is the better pick: it passed more tasks on the AIGROW small-business benchmark and has the lower list price. GPT-5.6 Luna passed 16 of 20 tasks and costs $0.20 in and $1.20 out per million tokens; Gemini 3.5 Flash-Lite passed 7 and costs $0.30 in and $2.50 out.
AIGROW credit covers Claude Opus 5.5, Claude Fable 5.2, Claude Fable 5.1, GPT-6 Astra, Claude Sonnet 5.5, GPT-6.1 Sol, GPT-6.1 Terra, Grok 4.7 and Gemini 4 Argon. GPT-6.1 Sol below list price
$25 a month brings $110 of API credit and cancels any time; $25 once buys $100. US dollars, standard rate, shortest context band. Cost per pass from the AIGROW small-business benchmark. Newer comparison: GPT-6 Luna vs Gemini 3.5 Flash-Lite
- GPT-5.6 Luna
- $0.677
- Tasks passed
- 16 of 20
- Gemini 3.5 Flash-Lite
- $2.47
- Tasks passed
- 7 of 20
AIGROW small-business benchmark, failed runs included.
Budget models from OpenAI and Google, both aimed at high-volume tasks. GPT-5.6 Luna costs $0.677 per 1,000 passing answers on the AIGROW small-business benchmark, Gemini 3.5 Flash-Lite $2.47. 1,000 support replies cost $1.90 on Gemini 3.5 Flash-Lite and $1.08 on GPT-5.6 Luna, so Gemini 3.5 Flash-Lite costs 76% more.
What each one costs
The API price per million tokens and the cheapest app plan with each model, from the makers’ own pages. Each name opens that model’s full price page.
- GPT-5.6 Luna
- On the OpenAI API, GPT-5.6 Luna costs $0.20 per million input tokens and $1.20 per million output tokens. In ChatGPT, the cheapest plan with it is Plus at $20/mo. Plan prices read 22 October 2026.
- Gemini 3.5 Flash-Lite
- On the Google API, Gemini 3.5 Flash-Lite costs $0.30 per million input tokens and $2.50 per million output tokens.
Side by side
Each maker’s published rate for its standard tier. Cached input is what a repeated prompt prefix costs once the provider has stored it.
| Fact | GPT-5.6 Luna | Gemini 3.5 Flash-Lite |
|---|---|---|
| Maker | OpenAI | |
| Tier | Small and fast | Small and fast |
| Input, per M tokens | $0.20 | $0.30 |
| Output, per M tokens | $1.20 | $2.50 |
| Cached input | $0.02 | $0.03 |
| Context window | 1.05M | 1.05M |
| Released | 9 Jul 2026 | 21 Jul 2026 |
| Weights | Closed weights | Closed weights |
What a job costs on each
1,000 runs of each job at the two list prices. The gap moves from job to job because the models price input, output and cached context differently.
| Job | GPT-5.6 Luna | Gemini 3.5 Flash-Lite | Cheaper |
|---|---|---|---|
| Support reply3,000 in, 400 out. | $1.08 | $1.90 | GPT-5.6 Luna, 43% less |
| Document summary25,000 in, 1,000 out. | $6.20 | $10.00 | GPT-5.6 Luna, 38% less |
| Agent task80,000 in (70,000 cached), 3,000 out. | $7.00 | $12.60 | GPT-5.6 Luna, 44% less |
The token counts are ours, chosen to look like real work; the prices are the makers’. A model with no published cache price bills the agent task’s repeated context at its full input rate.
The small print
What each base rate leaves out, from the makers’ own pages: surcharges, discounts, promotions and cache pricing.
- GPT-5.6 Luna
- Nano tier of the 5.6 family. Price cut 80% on 2026-07-30. Requests above 272K input tokens bill 2x input and 1.5x output ($0.40 / $1.80). Cache write $0.25. Batch and Flex 50% off. Data residency adds 10%. OpenAI’s pricing page
- Gemini 3.5 Flash-Lite
- Same price for text, image, video and audio input. Batch 50% off. Cache storage $1.00 per MTok per hour. Google’s pricing page
Other comparisons
Every head to head on the list that involves GPT-5.6 Luna or Gemini 3.5 Flash-Lite.
Compare GPT-5.6 Luna and Gemini 3.5 Flash-Lite with 52 other models
The price list sets every model’s input and output price side by side, with what a support reply, a document summary and an agent task cost on each.
Prices checked 12 November 2026