Is GPT-5.6 Luna or Gemini 3.8 Flash cheaper?

GPT-5.6 Luna is cheaper for a typical request of 1,000 input and 500 output tokens: $0.0008 versus $0.002625 for Gemini 3.8 Flash, about 70% less.

What are the per-token prices of GPT-5.6 Luna and Gemini 3.8 Flash?

GPT-5.6 Luna costs $0.20 input and $1.20 output per million tokens. Gemini 3.8 Flash costs $0.75 input and $3.75 output per million tokens.

Which has the larger context window, GPT-5.6 Luna or Gemini 3.8 Flash?

GPT-5.6 Luna has the larger context window: 1.05M tokens versus 1.05M for Gemini 3.8 Flash.

OpenAI vs Google

GPT-5.6 Luna vs Gemini 3.8 Flash: pricing comparison

GPT-5.6 Luna costs 3.3× less than Gemini 3.8 Flash for a typical 1,000-input, 500-output request. Here is how the two compare on price, context and discounts.

Prices last updated: September 25, 2026

	GPT-5.6 Luna	Gemini 3.8 Flash
Provider	OpenAI	Google
Input per 1M tokens	$0.20	$0.75
Output per 1M tokens	$1.20	$3.75
Context window	1.05M	1.05M
Batch discount	50% off	50% off
Typical request (1,000 in / 500 out)	$0.0008	$0.002625
Monthly at 1,000 requests/day	$24.00	$78.75

GPT-5.6 Luna: Inputs above 272K tokens are billed at a higher long-context rate ($0.40 / $1.80).

Gemini 3.8 Flash: Promotional rate through 31 December 2026; scheduled to rise to $1.50 / $7.50.

Compare with your own numbers

Input tokens

Output tokens

Requests / day

GPT-5.6 Luna per request: $0.0008
Per month: $24.00

Gemini 3.8 Flash per request: $0.002625
Per month: $78.75

Cost by task

Cost per 1,000 requests at standard prices.
Task	Tokens (in / out)	GPT-5.6 Luna	Gemini 3.8 Flash
Short chat reply	500 / 300	$0.46	$1.50
RAG answer	6,000 / 600	$1.92	$6.75
Summarize a long document	12,000 / 1,000	$3.60	$12.75
Output-heavy generation	1,000 / 4,000	$5.00	$15.75

Output tokens usually dominate the bill — see input vs output token cost.

Frequently asked questions

Is GPT-5.6 Luna or Gemini 3.8 Flash cheaper?: GPT-5.6 Luna is cheaper for a typical request of 1,000 input and 500 output tokens: $0.0008 versus $0.002625 for Gemini 3.8 Flash, about 70% less.
What are the per-token prices of GPT-5.6 Luna and Gemini 3.8 Flash?: GPT-5.6 Luna costs $0.20 input and $1.20 output per million tokens. Gemini 3.8 Flash costs $0.75 input and $3.75 output per million tokens.
Which has the larger context window, GPT-5.6 Luna or Gemini 3.8 Flash?: GPT-5.6 Luna has the larger context window: 1.05M tokens versus 1.05M for Gemini 3.8 Flash.

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